If the memmap is virtually contiguous (either because we're using a
virtually mapped memmap or because we don't support a discontig memmap at
all), then we can implement nth_page() by simple addition. Contrary to
popular belief, the compiler is not able to optimise this itself for a
vmemmap configuration. This reduces one example user (sg.c) by four
instructions:
struct page *page = nth_page(rsv_schp->pages[k], offset >> PAGE_SHIFT);
before:
49 8b 45 70 mov 0x70(%r13),%rax
48 63 c9 movslq %ecx,%rcx
48 c1 eb 0c shr $0xc,%rbx
48 8b 04 c8 mov (%rax,%rcx,8),%rax
48 2b 05 00 00 00 00 sub 0x0(%rip),%rax
R_X86_64_PC32 vmemmap_base-0x4
48 c1 f8 06 sar $0x6,%rax
48 01 d8 add %rbx,%rax
48 c1 e0 06 shl $0x6,%rax
48 03 05 00 00 00 00 add 0x0(%rip),%rax
R_X86_64_PC32 vmemmap_base-0x4
after:
49 8b 45 70 mov 0x70(%r13),%rax
48 63 c9 movslq %ecx,%rcx
48 c1 eb 0c shr $0xc,%rbx
48 c1 e3 06 shl $0x6,%rbx
48 03 1c c8 add (%rax,%rcx,8),%rbx
Link: https://lkml.kernel.org/r/20210413194625.1472345-1-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Tejun Heo <tj@kernel.org>
Cc: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: Douglas Gilbert <dougg@torque.net>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add the details for figuring out which parts of the kernel image is being
freed on initmem case.
Before:
Freeing unused kernel memory: 1024K
After:
Freeing unused kernel image (initmem) memory: 1024K
Link: https://lkml.kernel.org/r/1622706274-4533-1-git-send-email-js07.lee@samsung.com
Signed-off-by: Jungseung Lee <js07.lee@samsung.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "mm: Add vma_lookup()", v2.
Many places in the kernel use find_vma() to get a vma and then check the
start address of the vma to ensure the next vma was not returned.
Other places use the find_vma_intersection() call with add, addr + 1 as
the range; looking for just the vma at a specific address.
The third use of find_vma() is by developers who do not know that the
function starts searching at the provided address upwards for the next
vma. This results in a bug that is often overlooked for a long time.
Adding the new vma_lookup() function will allow for cleaner code by
removing the find_vma() calls which check limits, making
find_vma_intersection() calls of a single address to be shorter, and
potentially reduce the incorrect uses of find_vma().
This patch (of 22):
Many places in the kernel use find_vma() to get a vma and then check the
start address of the vma to ensure the next vma was not returned.
Other places use the find_vma_intersection() call with add, addr + 1 as
the range; looking for just the vma at a specific address.
The third use of find_vma() is by developers who do not know that the
function starts searching at the provided address upwards for the next
vma. This results in a bug that is often overlooked for a long time.
Adding the new vma_lookup() function will allow for cleaner code by
removing the find_vma() calls which check limits, making
find_vma_intersection() calls of a single address to be shorter, and
potentially reduce the incorrect uses of find_vma().
Also change find_vma_intersection() comments and declaration to be of the
correct length and add kernel documentation style comment.
Link: https://lkml.kernel.org/r/20210521174745.2219620-1-Liam.Howlett@Oracle.com
Link: https://lkml.kernel.org/r/20210521174745.2219620-2-Liam.Howlett@Oracle.com
Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Reviewed-by: Laurent Dufour <ldufour@linux.ibm.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Davidlohr Bueso <dbueso@suse.de>
Cc: David Miller <davem@davemloft.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
has_pinned 32bit can be packed in the MMF_HAS_PINNED bit as a noop
cleanup.
Any atomic_inc/dec to the mm cacheline shared by all threads in pin-fast
would reintroduce a loss of SMP scalability to pin-fast, so there's no
future potential usefulness to keep an atomic in the mm for this.
set_bit(MMF_HAS_PINNED) will be theoretically a bit slower than WRITE_ONCE
(atomic_set is equivalent to WRITE_ONCE), but the set_bit (just like
atomic_set after this commit) has to be still issued only once per "mm",
so the difference between the two will be lost in the noise.
will-it-scale "mmap2" shows no change in performance with enterprise
config as expected.
will-it-scale "pin_fast" retains the > 4000% SMP scalability performance
improvement against upstream as expected.
This is a noop as far as overall performance and SMP scalability are
concerned.
[peterx@redhat.com: pack has_pinned in MMF_HAS_PINNED]
Link: https://lkml.kernel.org/r/YJqWESqyxa8OZA+2@t490s
[akpm@linux-foundation.org: coding style fixes]
[peterx@redhat.com: fix build for task_mmu.c, introduce mm_set_has_pinned_flag, fix comments]
Link: https://lkml.kernel.org/r/20210507150553.208763-4-peterx@redhat.com
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Kirill Shutemov <kirill@shutemov.name>
Cc: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
These functions implement the address_space ->set_page_dirty operation and
should live in pagemap.h, not mm.h so that the rest of the kernel doesn't
get funny ideas about calling them directly.
Link: https://lkml.kernel.org/r/20210615162342.1669332-7-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "Further set_page_dirty cleanups".
Prompted by Christoph's recent patches, here are some more patches to
improve the state of set_page_dirty(). They're all from the folio tree,
so they've been tested to a certain extent.
This patch (of 6):
Nothing in __set_page_dirty() is specific to buffer_head, so move it to
mm/page-writeback.c. That removes the only caller of
account_page_dirtied() outside of page-writeback.c, so make it static.
Link: https://lkml.kernel.org/r/20210615162342.1669332-1-willy@infradead.org
Link: https://lkml.kernel.org/r/20210615162342.1669332-2-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
On systems with memory nodes sorted in descending order, for instance Dell
Precision WorkStation T5500, the struct pages for higher PFNs and
respectively lower nodes, could be overwritten by the initialization of
struct pages corresponding to the holes in the memory sections.
For example for the below memory layout
[ 0.245624] Early memory node ranges
[ 0.248496] node 1: [mem 0x0000000000001000-0x0000000000090fff]
[ 0.251376] node 1: [mem 0x0000000000100000-0x00000000dbdf8fff]
[ 0.254256] node 1: [mem 0x0000000100000000-0x0000001423ffffff]
[ 0.257144] node 0: [mem 0x0000001424000000-0x0000002023ffffff]
the range 0x1424000000 - 0x1428000000 in the beginning of node 0 starts in
the middle of a section and will be considered as a hole during the
initialization of the last section in node 1.
The wrong initialization of the memory map causes panic on boot when
CONFIG_DEBUG_VM is enabled.
Reorder loop order of the memory map initialization so that the outer loop
will always iterate over populated memory regions in the ascending order
and the inner loop will select the zone corresponding to the PFN range.
This way initialization of the struct pages for the memory holes will be
always done for the ranges that are actually not populated.
[akpm@linux-foundation.org: coding style fixes]
Link: https://lkml.kernel.org/r/YNXlMqBbL+tBG7yq@kernel.org
Link: https://bugzilla.kernel.org/show_bug.cgi?id=213073
Link: https://lkml.kernel.org/r/20210624062305.10940-1-rppt@kernel.org
Fixes: 0740a50b9b ("mm/page_alloc.c: refactor initialization of struct page for holes in memory layout")
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Cc: Boris Petkov <bp@alien8.de>
Cc: Robert Shteynfeld <robert.shteynfeld@gmail.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: David Hildenbrand <david@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull user namespace rlimit handling update from Eric Biederman:
"This is the work mainly by Alexey Gladkov to limit rlimits to the
rlimits of the user that created a user namespace, and to allow users
to have stricter limits on the resources created within a user
namespace."
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
cred: add missing return error code when set_cred_ucounts() failed
ucounts: Silence warning in dec_rlimit_ucounts
ucounts: Set ucount_max to the largest positive value the type can hold
kselftests: Add test to check for rlimit changes in different user namespaces
Reimplement RLIMIT_MEMLOCK on top of ucounts
Reimplement RLIMIT_SIGPENDING on top of ucounts
Reimplement RLIMIT_MSGQUEUE on top of ucounts
Reimplement RLIMIT_NPROC on top of ucounts
Use atomic_t for ucounts reference counting
Add a reference to ucounts for each cred
Increase size of ucounts to atomic_long_t
Trivial conflicts in net/can/isotp.c and
tools/testing/selftests/net/mptcp/mptcp_connect.sh
scaled_ppm_to_ppb() was moved from drivers/ptp/ptp_clock.c
to include/linux/ptp_clock_kernel.h in -next so re-apply
the fix there.
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
There is a race between THP unmapping and truncation, when truncate sees
pmd_none() and skips the entry, after munmap's zap_huge_pmd() cleared
it, but before its page_remove_rmap() gets to decrement
compound_mapcount: generating false "BUG: Bad page cache" reports that
the page is still mapped when deleted. This commit fixes that, but not
in the way I hoped.
The first attempt used try_to_unmap(page, TTU_SYNC|TTU_IGNORE_MLOCK)
instead of unmap_mapping_range() in truncate_cleanup_page(): it has
often been an annoyance that we usually call unmap_mapping_range() with
no pages locked, but there apply it to a single locked page.
try_to_unmap() looks more suitable for a single locked page.
However, try_to_unmap_one() contains a VM_BUG_ON_PAGE(!pvmw.pte,page):
it is used to insert THP migration entries, but not used to unmap THPs.
Copy zap_huge_pmd() and add THP handling now? Perhaps, but their TLB
needs are different, I'm too ignorant of the DAX cases, and couldn't
decide how far to go for anon+swap. Set that aside.
The second attempt took a different tack: make no change in truncate.c,
but modify zap_huge_pmd() to insert an invalidated huge pmd instead of
clearing it initially, then pmd_clear() between page_remove_rmap() and
unlocking at the end. Nice. But powerpc blows that approach out of the
water, with its serialize_against_pte_lookup(), and interesting pgtable
usage. It would need serious help to get working on powerpc (with a
minor optimization issue on s390 too). Set that aside.
Just add an "if (page_mapped(page)) synchronize_rcu();" or other such
delay, after unmapping in truncate_cleanup_page()? Perhaps, but though
that's likely to reduce or eliminate the number of incidents, it would
give less assurance of whether we had identified the problem correctly.
This successful iteration introduces "unmap_mapping_page(page)" instead
of try_to_unmap(), and goes the usual unmap_mapping_range_tree() route,
with an addition to details. Then zap_pmd_range() watches for this
case, and does spin_unlock(pmd_lock) if so - just like
page_vma_mapped_walk() now does in the PVMW_SYNC case. Not pretty, but
safe.
Note that unmap_mapping_page() is doing a VM_BUG_ON(!PageLocked) to
assert its interface; but currently that's only used to make sure that
page->mapping is stable, and zap_pmd_range() doesn't care if the page is
locked or not. Along these lines, in invalidate_inode_pages2_range()
move the initial unmap_mapping_range() out from under page lock, before
then calling unmap_mapping_page() under page lock if still mapped.
Link: https://lkml.kernel.org/r/a2a4a148-cdd8-942c-4ef8-51b77f643dbe@google.com
Fixes: fc127da085 ("truncate: handle file thp")
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jue Wang <juew@google.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Wang Yugui <wangyugui@e16-tech.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently the common definition of function_nocfi() is provided by
<linux/mm.h>, and architectures are expected to provide a definition in
<asm/memory.h>. Due to header dependencies, this can make it hard to use
function_nocfi() in low-level headers.
As function_nocfi() has no dependency on any mm code, nor on any memory
definitions, it doesn't need to live in <linux/mm.h> or <asm/memory.h>.
Generally, it would make more sense for it to live in
<linux/compiler.h>, where an architecture can override it in
<asm/compiler.h>.
Move the definitions accordingly.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Sami Tolvanen <samitolvanen@google.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210602153701.35957-1-mark.rutland@arm.com
This is needed by the page_pool to avoid recycling a page not allocated
via page_pool.
The page->signature field is aliased to page->lru.next and
page->compound_head, but it can't be set by mistake because the
signature value is a bad pointer, and can't trigger a false positive
in PageTail() because the last bit is 0.
Co-developed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Matteo Croce <mcroce@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Patch series "mm/hugetlb: Fix issues on file sealing and fork", v2.
Hugh reported issue with F_SEAL_FUTURE_WRITE not applied correctly to
hugetlbfs, which I can easily verify using the memfd_test program, which
seems that the program is hardly run with hugetlbfs pages (as by default
shmem).
Meanwhile I found another probably even more severe issue on that hugetlb
fork won't wr-protect child cow pages, so child can potentially write to
parent private pages. Patch 2 addresses that.
After this series applied, "memfd_test hugetlbfs" should start to pass.
This patch (of 2):
F_SEAL_FUTURE_WRITE is missing for hugetlb starting from the first day.
There is a test program for that and it fails constantly.
$ ./memfd_test hugetlbfs
memfd-hugetlb: CREATE
memfd-hugetlb: BASIC
memfd-hugetlb: SEAL-WRITE
memfd-hugetlb: SEAL-FUTURE-WRITE
mmap() didn't fail as expected
Aborted (core dumped)
I think it's probably because no one is really running the hugetlbfs test.
Fix it by checking FUTURE_WRITE also in hugetlbfs_file_mmap() as what we
do in shmem_mmap(). Generalize a helper for that.
Link: https://lkml.kernel.org/r/20210503234356.9097-1-peterx@redhat.com
Link: https://lkml.kernel.org/r/20210503234356.9097-2-peterx@redhat.com
Fixes: ab3948f58f ("mm/memfd: add an F_SEAL_FUTURE_WRITE seal to memfd")
Signed-off-by: Peter Xu <peterx@redhat.com>
Reported-by: Hugh Dickins <hughd@google.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Joel Fernandes (Google) <joel@joelfernandes.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
On some platforms ZERO_PAGE(0) might end-up in a movable zone. Do not
migrate zero page in gup during longterm pinning as migration of zero page
is not allowed.
For example, in x86 QEMU with 16G of memory and kernelcore=5G parameter, I
see the following:
Boot#1: zero_pfn 0x48a8d zero_pfn zone: ZONE_DMA32
Boot#2: zero_pfn 0x20168d zero_pfn zone: ZONE_MOVABLE
On x86, empty_zero_page is declared in .bss and depending on the loader
may end up in different physical locations during boots.
Also, move is_zero_pfn() my_zero_pfn() functions under CONFIG_MMU, because
zero_pfn that they are using is declared in memory.c which is compiled
with CONFIG_MMU.
Link: https://lkml.kernel.org/r/20210215161349.246722-9-pasha.tatashin@soleen.com
Signed-off-by: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: James Morris <jmorris@namei.org>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sasha Levin <sashal@kernel.org>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Tyler Hicks <tyhicks@linux.microsoft.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
PF_MEMALLOC_PIN is only honored for CMA pages, extend this flag to work
for any allocations from ZONE_MOVABLE by removing __GFP_MOVABLE from
gfp_mask when this flag is passed in the current context.
Add is_pinnable_page() to return true if page is in a pinnable page. A
pinnable page is not in ZONE_MOVABLE and not of MIGRATE_CMA type.
Link: https://lkml.kernel.org/r/20210215161349.246722-8-pasha.tatashin@soleen.com
Signed-off-by: Pavel Tatashin <pasha.tatashin@soleen.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: James Morris <jmorris@namei.org>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sasha Levin <sashal@kernel.org>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Tyler Hicks <tyhicks@linux.microsoft.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "userfaultfd: add minor fault handling", v9.
Overview
========
This series adds a new userfaultfd feature, UFFD_FEATURE_MINOR_HUGETLBFS.
When enabled (via the UFFDIO_API ioctl), this feature means that any
hugetlbfs VMAs registered with UFFDIO_REGISTER_MODE_MISSING will *also*
get events for "minor" faults. By "minor" fault, I mean the following
situation:
Let there exist two mappings (i.e., VMAs) to the same page(s) (shared
memory). One of the mappings is registered with userfaultfd (in minor
mode), and the other is not. Via the non-UFFD mapping, the underlying
pages have already been allocated & filled with some contents. The UFFD
mapping has not yet been faulted in; when it is touched for the first
time, this results in what I'm calling a "minor" fault. As a concrete
example, when working with hugetlbfs, we have huge_pte_none(), but
find_lock_page() finds an existing page.
We also add a new ioctl to resolve such faults: UFFDIO_CONTINUE. The idea
is, userspace resolves the fault by either a) doing nothing if the
contents are already correct, or b) updating the underlying contents using
the second, non-UFFD mapping (via memcpy/memset or similar, or something
fancier like RDMA, or etc...). In either case, userspace issues
UFFDIO_CONTINUE to tell the kernel "I have ensured the page contents are
correct, carry on setting up the mapping".
Use Case
========
Consider the use case of VM live migration (e.g. under QEMU/KVM):
1. While a VM is still running, we copy the contents of its memory to a
target machine. The pages are populated on the target by writing to the
non-UFFD mapping, using the setup described above. The VM is still running
(and therefore its memory is likely changing), so this may be repeated
several times, until we decide the target is "up to date enough".
2. We pause the VM on the source, and start executing on the target machine.
During this gap, the VM's user(s) will *see* a pause, so it is desirable to
minimize this window.
3. Between the last time any page was copied from the source to the target, and
when the VM was paused, the contents of that page may have changed - and
therefore the copy we have on the target machine is out of date. Although we
can keep track of which pages are out of date, for VMs with large amounts of
memory, it is "slow" to transfer this information to the target machine. We
want to resume execution before such a transfer would complete.
4. So, the guest begins executing on the target machine. The first time it
touches its memory (via the UFFD-registered mapping), userspace wants to
intercept this fault. Userspace checks whether or not the page is up to date,
and if not, copies the updated page from the source machine, via the non-UFFD
mapping. Finally, whether a copy was performed or not, userspace issues a
UFFDIO_CONTINUE ioctl to tell the kernel "I have ensured the page contents
are correct, carry on setting up the mapping".
We don't have to do all of the final updates on-demand. The userfaultfd manager
can, in the background, also copy over updated pages once it receives the map of
which pages are up-to-date or not.
Interaction with Existing APIs
==============================
Because this is a feature, a registered VMA could potentially receive both
missing and minor faults. I spent some time thinking through how the
existing API interacts with the new feature:
UFFDIO_CONTINUE cannot be used to resolve non-minor faults, as it does not
allocate a new page. If UFFDIO_CONTINUE is used on a non-minor fault:
- For non-shared memory or shmem, -EINVAL is returned.
- For hugetlb, -EFAULT is returned.
UFFDIO_COPY and UFFDIO_ZEROPAGE cannot be used to resolve minor faults.
Without modifications, the existing codepath assumes a new page needs to
be allocated. This is okay, since userspace must have a second
non-UFFD-registered mapping anyway, thus there isn't much reason to want
to use these in any case (just memcpy or memset or similar).
- If UFFDIO_COPY is used on a minor fault, -EEXIST is returned.
- If UFFDIO_ZEROPAGE is used on a minor fault, -EEXIST is returned (or -EINVAL
in the case of hugetlb, as UFFDIO_ZEROPAGE is unsupported in any case).
- UFFDIO_WRITEPROTECT simply doesn't work with shared memory, and returns
-ENOENT in that case (regardless of the kind of fault).
Future Work
===========
This series only supports hugetlbfs. I have a second series in flight to
support shmem as well, extending the functionality. This series is more
mature than the shmem support at this point, and the functionality works
fully on hugetlbfs, so this series can be merged first and then shmem
support will follow.
This patch (of 6):
This feature allows userspace to intercept "minor" faults. By "minor"
faults, I mean the following situation:
Let there exist two mappings (i.e., VMAs) to the same page(s). One of the
mappings is registered with userfaultfd (in minor mode), and the other is
not. Via the non-UFFD mapping, the underlying pages have already been
allocated & filled with some contents. The UFFD mapping has not yet been
faulted in; when it is touched for the first time, this results in what
I'm calling a "minor" fault. As a concrete example, when working with
hugetlbfs, we have huge_pte_none(), but find_lock_page() finds an existing
page.
This commit adds the new registration mode, and sets the relevant flag on
the VMAs being registered. In the hugetlb fault path, if we find that we
have huge_pte_none(), but find_lock_page() does indeed find an existing
page, then we have a "minor" fault, and if the VMA has the userfaultfd
registration flag, we call into userfaultfd to handle it.
This is implemented as a new registration mode, instead of an API feature.
This is because the alternative implementation has significant drawbacks
[1].
However, doing it this was requires we allocate a VM_* flag for the new
registration mode. On 32-bit systems, there are no unused bits, so this
feature is only supported on architectures with
CONFIG_ARCH_USES_HIGH_VMA_FLAGS. When attempting to register a VMA in
MINOR mode on 32-bit architectures, we return -EINVAL.
[1] https://lore.kernel.org/patchwork/patch/1380226/
[peterx@redhat.com: fix minor fault page leak]
Link: https://lkml.kernel.org/r/20210322175132.36659-1-peterx@redhat.com
Link: https://lkml.kernel.org/r/20210301222728.176417-1-axelrasmussen@google.com
Link: https://lkml.kernel.org/r/20210301222728.176417-2-axelrasmussen@google.com
Signed-off-by: Axel Rasmussen <axelrasmussen@google.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chinwen Chang <chinwen.chang@mediatek.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Lokesh Gidra <lokeshgidra@google.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: "Michal Koutn" <mkoutny@suse.com>
Cc: Michel Lespinasse <walken@google.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Shaohua Li <shli@fb.com>
Cc: Shawn Anastasio <shawn@anastas.io>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Steven Price <steven.price@arm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Adam Ruprecht <ruprecht@google.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Cannon Matthews <cannonmatthews@google.com>
Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Mina Almasry <almasrymina@google.com>
Cc: Oliver Upton <oupton@google.com>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The rlimit counter is tied to uid in the user_namespace. This allows
rlimit values to be specified in userns even if they are already
globally exceeded by the user. However, the value of the previous
user_namespaces cannot be exceeded.
Changelog
v11:
* Fix issue found by lkp robot.
v8:
* Fix issues found by lkp-tests project.
v7:
* Keep only ucounts for RLIMIT_MEMLOCK checks instead of struct cred.
v6:
* Fix bug in hugetlb_file_setup() detected by trinity.
Reported-by: kernel test robot <oliver.sang@intel.com>
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Alexey Gladkov <legion@kernel.org>
Link: https://lkml.kernel.org/r/970d50c70c71bfd4496e0e8d2a0a32feebebb350.1619094428.git.legion@kernel.org
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
mem_init_print_info() is called in mem_init() on each architecture, and
pass NULL argument, so using void argument and move it into mm_init().
Link: https://lkml.kernel.org/r/20210317015210.33641-1-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com> [x86]
Reviewed-by: Christophe Leroy <christophe.leroy@c-s.fr> [powerpc]
Acked-by: David Hildenbrand <david@redhat.com>
Tested-by: Anatoly Pugachev <matorola@gmail.com> [sparc64]
Acked-by: Russell King <rmk+kernel@armlinux.org.uk> [arm]
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Guo Ren <guoren@kernel.org>
Cc: Yoshinori Sato <ysato@users.osdn.me>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: "Peter Zijlstra" <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The kernel-doc script complains about
include/linux/mm.h:425: warning: wrong kernel-doc identifier on line:
* Fault flag definitions.
I don't know how to document a series of #defines, so turn these
definitions into an enum and document that instead.
Link: https://lkml.kernel.org/r/20210322195022.2143603-3-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
make htmldocs reports:
include/linux/mm.h:1341: warning: Excess function parameter 'Return' description in 'page_maybe_dma_pinned'
Fix a few other formatting nits while I'm editing this description.
Link: https://lkml.kernel.org/r/20210322195022.2143603-2-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
make htmldocs reports:
include/linux/mm.h:496: warning: Function parameter or member 'flags' not described in 'fault_flag_allow_retry_first'
Add a description.
Link: https://lkml.kernel.org/r/20210322195022.2143603-1-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This reverts commit cd544fd1dc.
As discussed in [1] this commit was a no-op because the mapping type was
checked in vma_to_resize before move_vma is ever called. This meant that
vm_ops->mremap() would never be called on such mappings. Furthermore,
we've since expanded support of MREMAP_DONTUNMAP to non-anonymous
mappings, and these special mappings are still protected by the existing
check of !VM_DONTEXPAND and !VM_PFNMAP which will result in a -EINVAL.
1. https://lkml.org/lkml/2020/12/28/2340
Link: https://lkml.kernel.org/r/20210323182520.2712101-2-bgeffon@google.com
Signed-off-by: Brian Geffon <bgeffon@google.com>
Acked-by: Hugh Dickins <hughd@google.com>
Reviewed-by: Dmitry Safonov <0x7f454c46@gmail.com>
Cc: Alejandro Colomar <alx.manpages@gmail.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: "Kirill A . Shutemov" <kirill@shutemov.name>
Cc: Lokesh Gidra <lokeshgidra@google.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: "Michael S . Tsirkin" <mst@redhat.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Peter Xu <peterx@redhat.com>
Cc: Sonny Rao <sonnyrao@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "add remap_pfn_range_notrack instead of reinventing it in i915", v2.
i915 has some reason to want to avoid the track_pfn_remap overhead in
remap_pfn_range. Add a function to the core VM to do just that rather
than reinventing the functionality poorly in the driver.
Note that the remap_io_sg path does get exercises when using Xorg on my
Thinkpad X1, so this should be considered lightly tested, I've not managed
to hit the remap_io_mapping path at all.
This patch (of 4):
Add a version of remap_pfn_range that does not call track_pfn_range. This
will be used to fix horrible abuses of VM internals in the i915 driver.
Link: https://lkml.kernel.org/r/20210326055505.1424432-1-hch@lst.de
Link: https://lkml.kernel.org/r/20210326055505.1424432-2-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Since commit 5a52c9df62 ("uprobe: use FOLL_SPLIT_PMD instead of
FOLL_SPLIT") and commit ba925fa350 ("s390/gmap: improve THP splitting")
FOLL_SPLIT has not been used anymore. Remove the dead code.
Link: https://lkml.kernel.org/r/20210330203900.9222-1-shy828301@gmail.com
Signed-off-by: Yang Shi <shy828301@gmail.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add an unpin_user_page_range_dirty_lock() API which takes a starting page
and how many consecutive pages we want to unpin and optionally dirty.
To that end, define another iterator for_each_compound_range() that
operates in page ranges as opposed to page array.
For users (like RDMA mr_dereg) where each sg represents a contiguous set
of pages, we're able to more efficiently unpin pages without having to
supply an array of pages much of what happens today with
unpin_user_pages().
Link: https://lkml.kernel.org/r/20210212130843.13865-4-joao.m.martins@oracle.com
Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Doug Ledford <dledford@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
page_mapping_file() is only used by some architectures, and then it
is usually only used in one place. Make it a static inline function
so other architectures don't have to carry this dead code.
Link: https://lkml.kernel.org/r/20210317123011.350118-1-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Cc: Huang Ying <ying.huang@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
- Bitmap support for "N" as alias for last bit
- kvfree_rcu updates
- mm_dump_obj() updates. (One of these is to mm, but was suggested by Andrew Morton.)
- RCU callback offloading update
- Polling RCU grace-period interfaces
- Realtime-related RCU updates
- Tasks-RCU updates
- Torture-test updates
- Torture-test scripting updates
- Miscellaneous fixes
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'core-rcu-2021-04-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull RCU updates from Ingo Molnar:
- Support for "N" as alias for last bit in bitmap parsing library (eg
using syntax like "nohz_full=2-N")
- kvfree_rcu updates
- mm_dump_obj() updates. (One of these is to mm, but was suggested by
Andrew Morton.)
- RCU callback offloading update
- Polling RCU grace-period interfaces
- Realtime-related RCU updates
- Tasks-RCU updates
- Torture-test updates
- Torture-test scripting updates
- Miscellaneous fixes
* tag 'core-rcu-2021-04-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (77 commits)
rcutorture: Test start_poll_synchronize_rcu() and poll_state_synchronize_rcu()
rcu: Provide polling interfaces for Tiny RCU grace periods
torture: Fix kvm.sh --datestamp regex check
torture: Consolidate qemu-cmd duration editing into kvm-transform.sh
torture: Print proper vmlinux path for kvm-again.sh runs
torture: Make TORTURE_TRUST_MAKE available in kvm-again.sh environment
torture: Make kvm-transform.sh update jitter commands
torture: Add --duration argument to kvm-again.sh
torture: Add kvm-again.sh to rerun a previous torture-test
torture: Create a "batches" file for build reuse
torture: De-capitalize TORTURE_SUITE
torture: Make upper-case-only no-dot no-slash scenario names official
torture: Rename SRCU-t and SRCU-u to avoid lowercase characters
torture: Remove no-mpstat error message
torture: Record kvm-test-1-run.sh and kvm-test-1-run-qemu.sh PIDs
torture: Record jitter start/stop commands
torture: Extract kvm-test-1-run-qemu.sh from kvm-test-1-run.sh
torture: Record TORTURE_KCONFIG_GDB_ARG in qemu-cmd
torture: Abstract jitter.sh start/stop into scripts
rcu: Provide polling interfaces for Tree RCU grace periods
...
- Clean up list_sort prototypes (Sami Tolvanen)
- Introduce CONFIG_CFI_CLANG for arm64 (Sami Tolvanen)
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Merge tag 'cfi-v5.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux
Pull CFI on arm64 support from Kees Cook:
"This builds on last cycle's LTO work, and allows the arm64 kernels to
be built with Clang's Control Flow Integrity feature. This feature has
happily lived in Android kernels for almost 3 years[1], so I'm excited
to have it ready for upstream.
The wide diffstat is mainly due to the treewide fixing of mismatched
list_sort prototypes. Other things in core kernel are to address
various CFI corner cases. The largest code portion is the CFI runtime
implementation itself (which will be shared by all architectures
implementing support for CFI). The arm64 pieces are Acked by arm64
maintainers rather than coming through the arm64 tree since carrying
this tree over there was going to be awkward.
CFI support for x86 is still under development, but is pretty close.
There are a handful of corner cases on x86 that need some improvements
to Clang and objtool, but otherwise works well.
Summary:
- Clean up list_sort prototypes (Sami Tolvanen)
- Introduce CONFIG_CFI_CLANG for arm64 (Sami Tolvanen)"
* tag 'cfi-v5.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
arm64: allow CONFIG_CFI_CLANG to be selected
KVM: arm64: Disable CFI for nVHE
arm64: ftrace: use function_nocfi for ftrace_call
arm64: add __nocfi to __apply_alternatives
arm64: add __nocfi to functions that jump to a physical address
arm64: use function_nocfi with __pa_symbol
arm64: implement function_nocfi
psci: use function_nocfi for cpu_resume
lkdtm: use function_nocfi
treewide: Change list_sort to use const pointers
bpf: disable CFI in dispatcher functions
kallsyms: strip ThinLTO hashes from static functions
kthread: use WARN_ON_FUNCTION_MISMATCH
workqueue: use WARN_ON_FUNCTION_MISMATCH
module: ensure __cfi_check alignment
mm: add generic function_nocfi macro
cfi: add __cficanonical
add support for Clang CFI
Pull RCU changes from Paul E. McKenney:
- Bitmap support for "N" as alias for last bit
- kvfree_rcu updates
- mm_dump_obj() updates. (One of these is to mm, but was suggested by Andrew Morton.)
- RCU callback offloading update
- Polling RCU grace-period interfaces
- Realtime-related RCU updates
- Tasks-RCU updates
- Torture-test updates
- Torture-test scripting updates
- Miscellaneous fixes
Signed-off-by: Ingo Molnar <mingo@kernel.org>
With CONFIG_CFI_CLANG, the compiler replaces function addresses
in instrumented C code with jump table addresses. This means that
__pa_symbol(function) returns the physical address of the jump table
entry instead of the actual function, which may not work as the jump
table code will immediately jump to a virtual address that may not be
mapped.
To avoid this address space confusion, this change adds a generic
definition for function_nocfi(), which architectures that support CFI
can override. The typical implementation of would use inline assembly
to take the function address, which avoids compiler instrumentation.
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210408182843.1754385-4-samitolvanen@google.com
The state of CONFIG_INIT_ON_ALLOC_DEFAULT_ON (and ...ON_FREE...) did not
change the assembly ordering of the static branches: they were always out
of line. Use the new jump_label macros to check the CONFIG settings to
default to the "expected" state, which slightly optimizes the resulting
assembly code.
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexander Potapenko <glider@google.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Link: https://lore.kernel.org/r/20210401232347.2791257-3-keescook@chromium.org
To allow performing tag checks on page_alloc addresses obtained via
page_address(), tag-based KASAN modes store tags for page_alloc
allocations in page->flags.
Currently, the default tag value stored in page->flags is 0x00.
Therefore, page_address() returns a 0x00ffff... address for pages that
were not allocated via page_alloc.
This might cause problems. A particular case we encountered is a
conflict with KFENCE. If a KFENCE-allocated slab object is being freed
via kfree(page_address(page) + offset), the address passed to kfree()
will get tagged with 0x00 (as slab pages keep the default per-page
tags). This leads to is_kfence_address() check failing, and a KFENCE
object ending up in normal slab freelist, which causes memory
corruptions.
This patch changes the way KASAN stores tag in page-flags: they are now
stored xor'ed with 0xff. This way, KASAN doesn't need to initialize
per-page flags for every created page, which might be slow.
With this change, page_address() returns natively-tagged (with 0xff)
pointers for pages that didn't have tags set explicitly.
This patch fixes the encountered conflict with KFENCE and prevents more
similar issues that can occur in the future.
Link: https://lkml.kernel.org/r/1a41abb11c51b264511d9e71c303bb16d5cb367b.1615475452.git.andreyknvl@google.com
Fixes: 2813b9c029 ("kasan, mm, arm64: tag non slab memory allocated via pagealloc")
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Marco Elver <elver@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Branislav Rankov <Branislav.Rankov@arm.com>
Cc: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We've got quite a few places (pte, pmd, pud) that explicitly checked
against whether we should break the cow right now during fork(). It's
easier to provide a helper, especially before we work the same thing on
hugetlbfs.
Since we'll reference is_cow_mapping() in mm.h, move it there too.
Actually it suites mm.h more since internal.h is mm/ only, but mm.h is
exported to the whole kernel. With that we should expect another patch to
use is_cow_mapping() whenever we can across the kernel since we do use it
quite a lot but it's always done with raw code against VM_* flags.
Link: https://lkml.kernel.org/r/20210217233547.93892-4-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: David Airlie <airlied@linux.ie>
Cc: David Gibson <david@gibson.dropbear.id.au>
Cc: Gal Pressman <galpress@amazon.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Kirill Shutemov <kirill@shutemov.name>
Cc: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Roland Scheidegger <sroland@vmware.com>
Cc: VMware Graphics <linux-graphics-maintainer@vmware.com>
Cc: Wei Zhang <wzam@amazon.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The mem_dump_obj() functionality adds a few hundred bytes, which is a
small price to pay. Except on kernels built with CONFIG_PRINTK=n, in
which mem_dump_obj() messages will be suppressed. This commit therefore
makes mem_dump_obj() be a static inline empty function on kernels built
with CONFIG_PRINTK=n and excludes all of its support functions as well.
This avoids kernel bloat on systems that cannot use mem_dump_obj().
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: <linux-mm@kvack.org>
Suggested-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Patch series "mm/hugetlb: follow_hugetlb_page() improvements", v2.
While looking at ZONE_DEVICE struct page reuse particularly the last
patch[0], I found two possible improvements for follow_hugetlb_page()
which is solely used for get_user_pages()/pin_user_pages().
The first patch batches page refcount updates while the second tidies up
storing the subpages/vmas. Both together bring the cost of slow variant
of gup() cost from ~87.6k usecs to ~5.8k usecs.
libhugetlbfs tests seem to pass as well gup_test benchmarks with hugetlbfs
vmas.
This patch (of 2):
follow_hugetlb_page() once it locks the pmd/pud, checks all its N subpages
in a huge page and grabs a reference for each one. Similar to gup-fast,
have follow_hugetlb_page() grab the head page refcount only after counting
all its subpages that are part of the just faulted huge page.
Consequently we reduce the number of atomics necessary to pin said huge
page, which improves non-fast gup() considerably:
- 16G with 1G huge page size
gup_test -f /mnt/huge/file -m 16384 -r 10 -L -S -n 512 -w
PIN_LONGTERM_BENCHMARK: ~87.6k us -> ~12.8k us
Link: https://lkml.kernel.org/r/20210128182632.24562-1-joao.m.martins@oracle.com
Link: https://lkml.kernel.org/r/20210128182632.24562-2-joao.m.martins@oracle.com
Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
adjust_managed_page_count() as called by free_reserved_page() properly
handles pages in a highmem zone, so we can reuse it for
free_highmem_page().
We can now get rid of totalhigh_pages_inc() and simplify
free_reserved_page().
Link: https://lkml.kernel.org/r/20210126182113.19892-3-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Wei Yang <richard.weiyang@linux.alibaba.com>
Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Cc: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
As David suggested, simply passing 'struct zone *zone' is enough. We can
get all needed information from 'struct zone*' easily.
Link: https://lkml.kernel.org/r/20210122135956.5946-4-bhe@redhat.com
Signed-off-by: Baoquan He <bhe@redhat.com>
Suggested-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Mike Rapoport <rppt@linux.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The current memmap_init_zone() only handles memory region inside one zone,
actually memmap_init() does the memmap init of one zone. So rename both
of them accordingly.
Link: https://lkml.kernel.org/r/20210122135956.5946-3-bhe@redhat.com
Signed-off-by: Baoquan He <bhe@redhat.com>
Reviewed-by: Mike Rapoport <rppt@linux.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "mm: clean up names and parameters of memmap_init_xxxx functions", v5.
This patchset corrects inappropriate function names of memmap_init_xxx,
and simplify parameters of functions in the code flow. And also fix a
prototype warning reported by lkp.
This patch (of 5);
Kernel test robot calling make with 'W=1' is triggering warning like
below for memmap_init_zone() function.
mm/page_alloc.c:6259:23: warning: no previous prototype for 'memmap_init_zone' [-Wmissing-prototypes]
6259 | void __meminit __weak memmap_init_zone(unsigned long size, int nid,
| ^~~~~~~~~~~~~~~~
Fix it by adding the function declaration in include/linux/mm.h. Since
memmap_init_zone() has a generic version with '__weak', the declaratoin in
ia64 header file can be simply removed.
Link: https://lkml.kernel.org/r/20210122135956.5946-1-bhe@redhat.com
Link: https://lkml.kernel.org/r/20210122135956.5946-2-bhe@redhat.com
Signed-off-by: Baoquan He <bhe@redhat.com>
Reported-by: kernel test robot <lkp@intel.com>
Reviewed-by: Mike Rapoport <rppt@linux.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
- replace mm/frame_vector.c by get_user_pages in misc/habana and
drm/exynos drivers, then move that into media as it's sole user
- close race in generic_access_phys
- s390 pci ioctl fix of this series landed in 5.11 already
- properly revoke iomem mappings (/dev/mem, pci files)
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Merge tag 'topic/iomem-mmap-vs-gup-2021-02-22' of git://anongit.freedesktop.org/drm/drm
Pull follow_pfn() updates from Daniel Vetter:
"Fixes around VM_FPNMAP and follow_pfn:
- replace mm/frame_vector.c by get_user_pages in misc/habana and
drm/exynos drivers, then move that into media as it's sole user
- close race in generic_access_phys
- s390 pci ioctl fix of this series landed in 5.11 already
- properly revoke iomem mappings (/dev/mem, pci files)"
* tag 'topic/iomem-mmap-vs-gup-2021-02-22' of git://anongit.freedesktop.org/drm/drm:
PCI: Revoke mappings like devmem
PCI: Also set up legacy files only after sysfs init
sysfs: Support zapping of binary attr mmaps
resource: Move devmem revoke code to resource framework
/dev/mem: Only set filp->f_mapping
PCI: Obey iomem restrictions for procfs mmap
mm: Close race in generic_access_phys
media: videobuf2: Move frame_vector into media subsystem
mm/frame-vector: Use FOLL_LONGTERM
misc/habana: Use FOLL_LONGTERM for userptr
misc/habana: Stop using frame_vector helpers
drm/exynos: Use FOLL_LONGTERM for g2d cmdlists
drm/exynos: Stop using frame_vector helpers
- Support for userspace to emulate Xen hypercalls
- Raise the maximum number of user memslots
- Scalability improvements for the new MMU. Instead of the complex
"fast page fault" logic that is used in mmu.c, tdp_mmu.c uses an
rwlock so that page faults are concurrent, but the code that can run
against page faults is limited. Right now only page faults take the
lock for reading; in the future this will be extended to some
cases of page table destruction. I hope to switch the default MMU
around 5.12-rc3 (some testing was delayed due to Chinese New Year).
- Cleanups for MAXPHYADDR checks
- Use static calls for vendor-specific callbacks
- On AMD, use VMLOAD/VMSAVE to save and restore host state
- Stop using deprecated jump label APIs
- Workaround for AMD erratum that made nested virtualization unreliable
- Support for LBR emulation in the guest
- Support for communicating bus lock vmexits to userspace
- Add support for SEV attestation command
- Miscellaneous cleanups
PPC:
- Support for second data watchpoint on POWER10
- Remove some complex workarounds for buggy early versions of POWER9
- Guest entry/exit fixes
ARM64
- Make the nVHE EL2 object relocatable
- Cleanups for concurrent translation faults hitting the same page
- Support for the standard TRNG hypervisor call
- A bunch of small PMU/Debug fixes
- Simplification of the early init hypercall handling
Non-KVM changes (with acks):
- Detection of contended rwlocks (implemented only for qrwlocks,
because KVM only needs it for x86)
- Allow __DISABLE_EXPORTS from assembly code
- Provide a saner follow_pfn replacements for modules
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm
Pull KVM updates from Paolo Bonzini:
"x86:
- Support for userspace to emulate Xen hypercalls
- Raise the maximum number of user memslots
- Scalability improvements for the new MMU.
Instead of the complex "fast page fault" logic that is used in
mmu.c, tdp_mmu.c uses an rwlock so that page faults are concurrent,
but the code that can run against page faults is limited. Right now
only page faults take the lock for reading; in the future this will
be extended to some cases of page table destruction. I hope to
switch the default MMU around 5.12-rc3 (some testing was delayed
due to Chinese New Year).
- Cleanups for MAXPHYADDR checks
- Use static calls for vendor-specific callbacks
- On AMD, use VMLOAD/VMSAVE to save and restore host state
- Stop using deprecated jump label APIs
- Workaround for AMD erratum that made nested virtualization
unreliable
- Support for LBR emulation in the guest
- Support for communicating bus lock vmexits to userspace
- Add support for SEV attestation command
- Miscellaneous cleanups
PPC:
- Support for second data watchpoint on POWER10
- Remove some complex workarounds for buggy early versions of POWER9
- Guest entry/exit fixes
ARM64:
- Make the nVHE EL2 object relocatable
- Cleanups for concurrent translation faults hitting the same page
- Support for the standard TRNG hypervisor call
- A bunch of small PMU/Debug fixes
- Simplification of the early init hypercall handling
Non-KVM changes (with acks):
- Detection of contended rwlocks (implemented only for qrwlocks,
because KVM only needs it for x86)
- Allow __DISABLE_EXPORTS from assembly code
- Provide a saner follow_pfn replacements for modules"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (192 commits)
KVM: x86/xen: Explicitly pad struct compat_vcpu_info to 64 bytes
KVM: selftests: Don't bother mapping GVA for Xen shinfo test
KVM: selftests: Fix hex vs. decimal snafu in Xen test
KVM: selftests: Fix size of memslots created by Xen tests
KVM: selftests: Ignore recently added Xen tests' build output
KVM: selftests: Add missing header file needed by xAPIC IPI tests
KVM: selftests: Add operand to vmsave/vmload/vmrun in svm.c
KVM: SVM: Make symbol 'svm_gp_erratum_intercept' static
locking/arch: Move qrwlock.h include after qspinlock.h
KVM: PPC: Book3S HV: Fix host radix SLB optimisation with hash guests
KVM: PPC: Book3S HV: Ensure radix guest has no SLB entries
KVM: PPC: Don't always report hash MMU capability for P9 < DD2.2
KVM: PPC: Book3S HV: Save and restore FSCR in the P9 path
KVM: PPC: remove unneeded semicolon
KVM: PPC: Book3S HV: Use POWER9 SLBIA IH=6 variant to clear SLB
KVM: PPC: Book3S HV: No need to clear radix host SLB before loading HPT guest
KVM: PPC: Book3S HV: Fix radix guest SLB side channel
KVM: PPC: Book3S HV: Remove support for running HPT guest on RPT host without mixed mode support
KVM: PPC: Book3S HV: Introduce new capability for 2nd DAWR
KVM: PPC: Book3S HV: Add infrastructure to support 2nd DAWR
...
- vDSO build improvements including support for building with BSD.
- Cleanup to the AMU support code and initialisation rework to support
cpufreq drivers built as modules.
- Removal of synthetic frame record from exception stack when entering
the kernel from EL0.
- Add support for the TRNG firmware call introduced by Arm spec
DEN0098.
- Cleanup and refactoring across the board.
- Avoid calling arch_get_random_seed_long() from
add_interrupt_randomness()
- Perf and PMU updates including support for Cortex-A78 and the v8.3
SPE extensions.
- Significant steps along the road to leaving the MMU enabled during
kexec relocation.
- Faultaround changes to initialise prefaulted PTEs as 'old' when
hardware access-flag updates are supported, which drastically
improves vmscan performance.
- CPU errata updates for Cortex-A76 (#1463225) and Cortex-A55
(#1024718)
- Preparatory work for yielding the vector unit at a finer granularity
in the crypto code, which in turn will one day allow us to defer
softirq processing when it is in use.
- Support for overriding CPU ID register fields on the command-line.
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Merge tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux
Pull arm64 updates from Will Deacon:
- vDSO build improvements including support for building with BSD.
- Cleanup to the AMU support code and initialisation rework to support
cpufreq drivers built as modules.
- Removal of synthetic frame record from exception stack when entering
the kernel from EL0.
- Add support for the TRNG firmware call introduced by Arm spec
DEN0098.
- Cleanup and refactoring across the board.
- Avoid calling arch_get_random_seed_long() from
add_interrupt_randomness()
- Perf and PMU updates including support for Cortex-A78 and the v8.3
SPE extensions.
- Significant steps along the road to leaving the MMU enabled during
kexec relocation.
- Faultaround changes to initialise prefaulted PTEs as 'old' when
hardware access-flag updates are supported, which drastically
improves vmscan performance.
- CPU errata updates for Cortex-A76 (#1463225) and Cortex-A55
(#1024718)
- Preparatory work for yielding the vector unit at a finer granularity
in the crypto code, which in turn will one day allow us to defer
softirq processing when it is in use.
- Support for overriding CPU ID register fields on the command-line.
* tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (85 commits)
drivers/perf: Replace spin_lock_irqsave to spin_lock
mm: filemap: Fix microblaze build failure with 'mmu_defconfig'
arm64: Make CPU_BIG_ENDIAN depend on ld.bfd or ld.lld 13.0.0+
arm64: cpufeatures: Allow disabling of Pointer Auth from the command-line
arm64: Defer enabling pointer authentication on boot core
arm64: cpufeatures: Allow disabling of BTI from the command-line
arm64: Move "nokaslr" over to the early cpufeature infrastructure
KVM: arm64: Document HVC_VHE_RESTART stub hypercall
arm64: Make kvm-arm.mode={nvhe, protected} an alias of id_aa64mmfr1.vh=0
arm64: Add an aliasing facility for the idreg override
arm64: Honor VHE being disabled from the command-line
arm64: Allow ID_AA64MMFR1_EL1.VH to be overridden from the command line
arm64: cpufeature: Add an early command-line cpufeature override facility
arm64: Extract early FDT mapping from kaslr_early_init()
arm64: cpufeature: Use IDreg override in __read_sysreg_by_encoding()
arm64: cpufeature: Add global feature override facility
arm64: Move SCTLR_EL1 initialisation to EL-agnostic code
arm64: Simplify init_el2_state to be non-VHE only
arm64: Move VHE-specific SPE setup to mutate_to_vhe()
arm64: Drop early setting of MDSCR_EL2.TPMS
...
- Documentation updates.
- Miscellaneous fixes.
- kfree_rcu() updates: Addition of mem_dump_obj() to provide allocator return
addresses to more easily locate bugs. This has a couple of RCU-related commits,
but is mostly MM. Was pulled in with akpm's agreement.
- Per-callback-batch tracking of numbers of callbacks,
which enables better debugging information and smarter
reactions to large numbers of callbacks.
- The first round of changes to allow CPUs to be runtime switched from and to
callback-offloaded state.
- CONFIG_PREEMPT_RT-related changes.
- RCU CPU stall warning updates.
- Addition of polling grace-period APIs for SRCU.
- Torture-test and torture-test scripting updates, including a "torture everything"
script that runs rcutorture, locktorture, scftorture, rcuscale, and refscale.
Plus does an allmodconfig build.
- nolibc fixes for the torture tests
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'core-rcu-2021-02-17' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull RCU updates from Ingo Molnar:
"These are the latest RCU updates for v5.12:
- Documentation updates.
- Miscellaneous fixes.
- kfree_rcu() updates: Addition of mem_dump_obj() to provide
allocator return addresses to more easily locate bugs. This has a
couple of RCU-related commits, but is mostly MM. Was pulled in with
akpm's agreement.
- Per-callback-batch tracking of numbers of callbacks, which enables
better debugging information and smarter reactions to large numbers
of callbacks.
- The first round of changes to allow CPUs to be runtime switched
from and to callback-offloaded state.
- CONFIG_PREEMPT_RT-related changes.
- RCU CPU stall warning updates.
- Addition of polling grace-period APIs for SRCU.
- Torture-test and torture-test scripting updates, including a
"torture everything" script that runs rcutorture, locktorture,
scftorture, rcuscale, and refscale. Plus does an allmodconfig
build.
- nolibc fixes for the torture tests"
* tag 'core-rcu-2021-02-17' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (130 commits)
percpu_ref: Dump mem_dump_obj() info upon reference-count underflow
rcu: Make call_rcu() print mem_dump_obj() info for double-freed callback
mm: Make mem_obj_dump() vmalloc() dumps include start and length
mm: Make mem_dump_obj() handle vmalloc() memory
mm: Make mem_dump_obj() handle NULL and zero-sized pointers
mm: Add mem_dump_obj() to print source of memory block
tools/rcutorture: Fix position of -lgcc in mkinitrd.sh
tools/nolibc: Fix position of -lgcc in the documented example
tools/nolibc: Emit detailed error for missing alternate syscall number definitions
tools/nolibc: Remove incorrect definitions of __ARCH_WANT_*
tools/nolibc: Get timeval, timespec and timezone from linux/time.h
tools/nolibc: Implement poll() based on ppoll()
tools/nolibc: Implement fork() based on clone()
tools/nolibc: Make getpgrp() fall back to getpgid(0)
tools/nolibc: Make dup2() rely on dup3() when available
tools/nolibc: Add the definition for dup()
rcutorture: Add rcutree.use_softirq=0 to RUDE01 and TASKS01
torture: Maintain torture-specific set of CPUs-online books
torture: Clean up after torture-test CPU hotplugging
rcutorture: Make object_debug also double call_rcu() heap object
...
Pull RCU updates from Paul E. McKenney:
- Documentation updates.
- Miscellaneous fixes.
- kfree_rcu() updates: Addition of mem_dump_obj() to provide allocator return
addresses to more easily locate bugs. This has a couple of RCU-related commits,
but is mostly MM. Was pulled in with akpm's agreement.
- Per-callback-batch tracking of numbers of callbacks,
which enables better debugging information and smarter
reactions to large numbers of callbacks.
- The first round of changes to allow CPUs to be runtime switched from and to
callback-offloaded state.
- CONFIG_PREEMPT_RT-related changes.
- RCU CPU stall warning updates.
- Addition of polling grace-period APIs for SRCU.
- Torture-test and torture-test scripting updates, including a "torture everything"
script that runs rcutorture, locktorture, scftorture, rcuscale, and refscale.
Plus does an allmodconfig build.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Currently, the follow_pfn function is exported for modules but
follow_pte is not. However, follow_pfn is very easy to misuse,
because it does not provide protections (so most of its callers
assume the page is writable!) and because it returns after having
already unlocked the page table lock.
Provide instead a simplified version of follow_pte that does
not have the pmdpp and range arguments. The older version
survives as follow_invalidate_pte() for use by fs/dax.c.
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The function only tests for page->index, so its argument should be
const.
Signed-off-by: Alexander Lobakin <alobakin@pm.me>
Reviewed-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
There are kernel facilities such as per-CPU reference counts that give
error messages in generic handlers or callbacks, whose messages are
unenlightening. In the case of per-CPU reference-count underflow, this
is not a problem when creating a new use of this facility because in that
case the bug is almost certainly in the code implementing that new use.
However, trouble arises when deploying across many systems, which might
exercise corner cases that were not seen during development and testing.
Here, it would be really nice to get some kind of hint as to which of
several uses the underflow was caused by.
This commit therefore exposes a mem_dump_obj() function that takes
a pointer to memory (which must still be allocated if it has been
dynamically allocated) and prints available information on where that
memory came from. This pointer can reference the middle of the block as
well as the beginning of the block, as needed by things like RCU callback
functions and timer handlers that might not know where the beginning of
the memory block is. These functions and handlers can use mem_dump_obj()
to print out better hints as to where the problem might lie.
The information printed can depend on kernel configuration. For example,
the allocation return address can be printed only for slab and slub,
and even then only when the necessary debug has been enabled. For slab,
build with CONFIG_DEBUG_SLAB=y, and either use sizes with ample space
to the next power of two or use the SLAB_STORE_USER when creating the
kmem_cache structure. For slub, build with CONFIG_SLUB_DEBUG=y and
boot with slub_debug=U, or pass SLAB_STORE_USER to kmem_cache_create()
if more focused use is desired. Also for slub, use CONFIG_STACKTRACE
to enable printing of the allocation-time stack trace.
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: <linux-mm@kvack.org>
Reported-by: Andrii Nakryiko <andrii@kernel.org>
[ paulmck: Convert to printing and change names per Joonsoo Kim. ]
[ paulmck: Move slab definition per Stephen Rothwell and kbuild test robot. ]
[ paulmck: Handle CONFIG_MMU=n case where vmalloc() is kmalloc(). ]
[ paulmck: Apply Vlastimil Babka feedback on slab.c kmem_provenance(). ]
[ paulmck: Extract more info from !SLUB_DEBUG per Joonsoo Kim. ]
[ paulmck: Explicitly check for small pointers per Naresh Kamboju. ]
Acked-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Tested-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
The fields of this struct are only ever read after being initialised, so
mark it 'const' before somebody tries to modify it again. GCC will then
complain (with an error) about modification of these fields after they
have been initialised, although LLVM currently allows them without even
a warning:
https://bugs.llvm.org/show_bug.cgi?id=48755
Hopefully, future versions of LLVM will emit a warning.
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Will Deacon <will@kernel.org>
Rather than modifying the 'address' field of the 'struct vm_fault'
passed to do_set_pte(), leave that to identify the real faulting address
and pass in the virtual address to be mapped by the new pte as a
separate argument.
This makes FAULT_FLAG_PREFAULT redundant, as a prefault entry can be
identified simply by comparing the new address parameter with the
faulting address, so remove the redundant flag at the same time.
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Will Deacon <will@kernel.org>
