The patch titled
Subject: mm: do not call do_fault_around for non-linear fault
has been added to the -mm tree. Its filename is
mm-do-not-call-do_fault_around-for-non-linear-fault.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-do-not-call-do_fault_around-for-non-linear-fault.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-do-not-call-do_fault_around-for-non-linear-fault.patch
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------------------------------------------------------
From: Konstantin Khlebnikov <koct9i@xxxxxxxxx>
Subject: mm: do not call do_fault_around for non-linear fault
Ingo Korb reported that "repeated mapping of the same file on tmpfs using
remap_file_pages sometimes triggers a BUG at mm/filemap.c:202 when the
process exits". He bisected the bug to d7c1755179b82d ("mm: implement
->map_pages for shmem/tmpfs"), although the bug was actually added by
8c6e50b0290c4 ("mm: introduce vm_ops->map_pages()").
Problem is caused by calling do_fault_around for _non-linear_ faiult. In
this case pgoff is shifted and might become negative during calculation.
Faulting around non-linear page-fault has no sense and breaks logic in
do_fault_around because pgoff is shifted.
Signed-off-by: Konstantin Khlebnikov <koct9i@xxxxxxxxx>
Reported-by: "Ingo Korb" <ingo.korb@xxxxxxxxxxxxxx>
Tested-by: "Ingo Korb" <ingo.korb@xxxxxxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Sasha Levin <sasha.levin@xxxxxxxxxx>
Cc: Dave Jones <davej@xxxxxxxxxx>
Cc: Ning Qu <quning@xxxxxxxxxx>
Cc: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> [3.15.x]
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memory.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff -puN mm/memory.c~mm-do-not-call-do_fault_around-for-non-linear-fault mm/memory.c
--- a/mm/memory.c~mm-do-not-call-do_fault_around-for-non-linear-fault
+++ a/mm/memory.c
@@ -2882,7 +2882,8 @@ static int do_read_fault(struct mm_struc
* if page by the offset is not ready to be mapped (cold cache or
* something).
*/
- if (vma->vm_ops->map_pages && fault_around_pages() > 1) {
+ if (vma->vm_ops->map_pages && !(flags & FAULT_FLAG_NONLINEAR) &&
+ fault_around_pages() > 1) {
pte = pte_offset_map_lock(mm, pmd, address, &ptl);
do_fault_around(vma, address, pte, pgoff, flags);
if (!pte_same(*pte, orig_pte))
_
Patches currently in -mm which might be from koct9i@xxxxxxxxx are
mm-do-not-call-do_fault_around-for-non-linear-fault.patch
shmem-fix-faulting-into-a-hole-not-taking-i_mutex.patch
shmem-fix-splicing-from-a-hole-while-its-punched.patch
mm-fs-fix-pessimization-in-hole-punching-pagecache.patch
mm-memoryc-use-entry-=-access_oncepte-in-handle_pte_fault.patch
include-linux-mmdebugh-add-vm_warn_once.patch
shmem-fix-double-uncharge-in-__shmem_file_setup.patch
shmem-update-memory-reservation-on-truncate.patch
mm-catch-memory-commitment-underflow.patch
mm-catch-memory-commitment-underflow-fix.patch
lib-idr-fix-out-of-bounds-pointer-dereference.patch
scripts-checkstackpl-automatically-handle-32-bit-and-64-bit-mode-for-arch=x86.patch
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