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authorTim Chen <tim.c.chen@linux.intel.com>2017-11-15 17:34:18 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2017-11-15 18:21:03 -0800
commita2e16731728a285bcfcece0feaaa8cf478d24022 (patch)
treeb4ff3a46cea6467267e250b127ca6865d00d44cc /arch/mn10300
parent3a50d14d0df5776e002a8683a290c87eeac93a21 (diff)
mm/swap_slots.c: fix race conditions in swap_slots cache init
Memory allocations can happen before the swap_slots cache initialization is completed during cpu bring up. If we are low on memory, we could call get_swap_page() and access swap_slots_cache before it is fully initialized. Add a check in get_swap_page() for initialized swap_slots_cache to prevent this condition. Similar check already exists in free_swap_slot. Also annotate the checks to indicate the likely condition. We also added a memory barrier to make sure that the locks initialization are done before the assignment of cache->slots and cache->slots_ret pointers. This ensures the assumption that it is safe to acquire the slots cache locks and use the slots cache when the corresponding cache->slots or cache->slots_ret pointers are non null. [akpm@linux-foundation.org: tidy up comment] [akpm@linux-foundation.org: fix spello in comment] Link: http://lkml.kernel.org/r/65a9d0f133f63e66bba37b53b2fd0464b7cae771.1500677066.git.tim.c.chen@linux.intel.com Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com> Reported-by: Wenwei Tao <wenwei.tww@alibaba-inc.com> Acked-by: Ying Huang <ying.huang@intel.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Hillf Danton <hdanton@sina.com> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/mn10300')
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