diff options
author | Konstantin Khlebnikov <khlebnikov@yandex-team.ru> | 2015-02-11 15:27:31 -0800 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2015-04-29 10:31:56 +0200 |
commit | 3b09542675a042106bd31a84b7c86b181751d029 (patch) | |
tree | 9b7efa4c69791367a66db36bf65987d86fc31efd /Makefile | |
parent | 620d77bda9fedb4dcd1271d3cbcbe099dff01f98 (diff) |
proc/pagemap: walk page tables under pte lock
commit 05fbf357d94152171bc50f8a369390f1f16efd89 upstream.
Lockless access to pte in pagemap_pte_range() might race with page
migration and trigger BUG_ON(!PageLocked()) in migration_entry_to_page():
CPU A (pagemap) CPU B (migration)
lock_page()
try_to_unmap(page, TTU_MIGRATION...)
make_migration_entry()
set_pte_at()
<read *pte>
pte_to_pagemap_entry()
remove_migration_ptes()
unlock_page()
if(is_migration_entry())
migration_entry_to_page()
BUG_ON(!PageLocked(page))
Also lockless read might be non-atomic if pte is larger than wordsize.
Other pte walkers (smaps, numa_maps, clear_refs) already lock ptes.
Fixes: 052fb0d635df ("proc: report file/anon bit in /proc/pid/pagemap")
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Reported-by: Andrey Ryabinin <a.ryabinin@samsung.com>
Reviewed-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: <stable@vger.kernel.org> [3.5+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'Makefile')
0 files changed, 0 insertions, 0 deletions