The patch titled
mm: sigbus instead of abusing oom
has been added to the -mm tree. Its filename is
mm-sigbus-instead-of-abusing-oom.patch
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------------------------------------------------------
Subject: mm: sigbus instead of abusing oom
From: Hugh Dickins <hugh.dickins@xxxxxxxxxxxxx>
When do_nonlinear_fault() realizes that the page table must have been
corrupted for it to have been called, it does print_bad_pte() and returns
... VM_FAULT_OOM, which is hard to understand.
It made some sense when I did it for 2.6.15, when do_page_fault() just
killed the current process; but nowadays it lets the OOM killer decide who
to kill - so page table corruption in one process would be liable to kill
another.
Change it to return VM_FAULT_SIGBUS instead: that doesn't guarantee that
the process will be killed, but is good enough for such a rare
abnormality, accompanied as it is by the "BUG: Bad page map" message.
And recent HWPOISON work has copied that code into do_swap_page(), when it
finds an impossible swap entry: fix that to VM_FAULT_SIGBUS too.
Signed-off-by: Hugh Dickins <hugh.dickins@xxxxxxxxxxxxx>
Cc: Izik Eidus <ieidus@xxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Nick Piggin <npiggin@xxxxxxx>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Lee Schermerhorn <Lee.Schermerhorn@xxxxxx>
Cc: Andi Kleen <andi@xxxxxxxxxxxxxx>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Reviewed-by: Wu Fengguang <fengguang.wu@xxxxxxxxx>
Reviewed-by: Minchan Kim <minchan.kim@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memory.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff -puN mm/memory.c~mm-sigbus-instead-of-abusing-oom mm/memory.c
--- a/mm/memory.c~mm-sigbus-instead-of-abusing-oom
+++ a/mm/memory.c
@@ -2527,7 +2527,7 @@ static int do_swap_page(struct mm_struct
ret = VM_FAULT_HWPOISON;
} else {
print_bad_pte(vma, address, orig_pte, NULL);
- ret = VM_FAULT_OOM;
+ ret = VM_FAULT_SIGBUS;
}
goto out;
}
@@ -2923,7 +2923,7 @@ static int do_nonlinear_fault(struct mm_
* Page table corrupted: show pte and kill process.
*/
print_bad_pte(vma, address, orig_pte, NULL);
- return VM_FAULT_OOM;
+ return VM_FAULT_SIGBUS;
}
pgoff = pte_to_pgoff(orig_pte);
_
Patches currently in -mm which might be from hugh.dickins@xxxxxxxxxxxxx are
origin.patch
mmap-dont-return-enomem-when-mapcount-is-temporarily-exceeded-in-munmap.patch
mmap-dont-return-enomem-when-mapcount-is-temporarily-exceeded-in-munmap-checkpatch-fixes.patch
vmalloc-adjust-gfp-mask-passed-on-nested-vmalloc-invocation.patch
swap_info-private-to-swapfilec.patch
swap_info-change-to-array-of-pointers.patch
swap_info-include-first_swap_extent.patch
swap_info-include-first_swap_extent-fix.patch
swap_info-include-first_swap_extent-fix-fix.patch
swap_info-miscellaneous-minor-cleanups.patch
swap_info-swap_has_cache-cleanups.patch
swap_info-swap_map-of-chars-not-shorts.patch
swap_info-swap-count-continuations.patch
swap_info-note-swap_map_shmem.patch
swap_info-reorder-its-fields.patch
rmap-fix-the-comment-for-try_to_unmap_anon.patch
oom_kill-use-rss-value-instead-of-vm-size-for-badness.patch
mm-define-page_mapping_flags.patch
mm-mlocking-in-try_to_unmap_one.patch
mm-config_mmu-for-pg_mlocked.patch
mm-pass-address-down-to-rmap-ones.patch
mm-stop-ptlock-enlarging-struct-page.patch
mm-sigbus-instead-of-abusing-oom.patch
elf-kill-use_elf_core_dump.patch
prio_tree-debugging-patch.patch
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