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  1. 20 11月, 2019 26 次提交
  3. 19 11月, 2019 3 次提交
    • M
      block: fix .bi_size overflow · a74e2556
      由 Ming Lei 提交于 
      commit 79d08f89bb1b5c2c1ff90d9bb95497ab9e8aa7e0 upstream

'bio->bi_iter.bi_size' is 'unsigned int', which at most hold 4G - 1
bytes.

Before 07173c3ec276 ("block: enable multipage bvecs"), one bio can
include very limited pages, and usually at most 256, so the fs bio
size won't be bigger than 1M bytes most of times.

Since we support multi-page bvec, in theory one fs bio really can
be added > 1M pages, especially in case of hugepage, or big writeback
with too many dirty pages. Then there is chance in which .bi_size
is overflowed.

Fixes this issue by using bio_full() to check if the added segment may
overflow .bi_size.
Signed-off-by: NHui Zhu <teawaterz@linux.alibaba.com>
Cc: Liu Yiding <liuyd.fnst@cn.fujitsu.com>
Cc: kernel test robot <rong.a.chen@intel.com>
Cc: "Darrick J. Wong" <darrick.wong@oracle.com>
Cc: linux-xfs@vger.kernel.org
Cc: linux-fsdevel@vger.kernel.org
Cc: stable@vger.kernel.org
Fixes: 07173c3ec276 ("block: enable multipage bvecs")
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NMing Lei <ming.lei@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>
Reviewed-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
      a74e2556
    • H
      mm, swap: fix race between swapoff and some swap operations · 73c29467
      由 Huang Ying 提交于 
      commit eb085574a7526c4375965c5fbf7e5b0c19cdd336 upstream.
Change SWP_VALID to (1 << 12).

When swapin is performed, after getting the swap entry information from
the page table, system will swap in the swap entry, without any lock held
to prevent the swap device from being swapoff.  This may cause the race
like below,

CPU 1				CPU 2
-----				-----
				do_swap_page
				  swapin_readahead
				    __read_swap_cache_async
swapoff				      swapcache_prepare
  p->swap_map = NULL		        __swap_duplicate
					  p->swap_map[?] /* !!! NULL pointer access */

Because swapoff is usually done when system shutdown only, the race may
not hit many people in practice.  But it is still a race need to be fixed.

To fix the race, get_swap_device() is added to check whether the specified
swap entry is valid in its swap device.  If so, it will keep the swap
entry valid via preventing the swap device from being swapoff, until
put_swap_device() is called.

Because swapoff() is very rare code path, to make the normal path runs as
fast as possible, rcu_read_lock/unlock() and synchronize_rcu() instead of
reference count is used to implement get/put_swap_device().  >From
get_swap_device() to put_swap_device(), RCU reader side is locked, so
synchronize_rcu() in swapoff() will wait until put_swap_device() is
called.

In addition to swap_map, cluster_info, etc.  data structure in the struct
swap_info_struct, the swap cache radix tree will be freed after swapoff,
so this patch fixes the race between swap cache looking up and swapoff
too.

Races between some other swap cache usages and swapoff are fixed too via
calling synchronize_rcu() between clearing PageSwapCache() and freeing
swap cache data structure.

Another possible method to fix this is to use preempt_off() +
stop_machine() to prevent the swap device from being swapoff when its data
structure is being accessed.  The overhead in hot-path of both methods is
similar.  The advantages of RCU based method are,

1. stop_machine() may disturb the normal execution code path on other
   CPUs.

2. File cache uses RCU to protect its radix tree.  If the similar
   mechanism is used for swap cache too, it is easier to share code
   between them.

3. RCU is used to protect swap cache in total_swapcache_pages() and
   exit_swap_address_space() already.  The two mechanisms can be
   merged to simplify the logic.

Link: http://lkml.kernel.org/r/20190522015423.14418-1-ying.huang@intel.com
Fixes: 235b6217 ("mm/swap: add cluster lock")
Signed-off-by: NHui Zhu <teawaterz@linux.alibaba.com>
Signed-off-by: N"Huang, Ying" <ying.huang@intel.com>
Reviewed-by: NAndrea Parri <andrea.parri@amarulasolutions.com>
Not-nacked-by: NHugh Dickins <hughd@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: Yang Shi <yang.shi@linux.alibaba.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: NYang Shi <yang.shi@linux.alibaba.com>
      73c29467
    • W
      vmscan: return NODE_RECLAIM_NOSCAN in node_reclaim() when CONFIG_NUMA is n · e431b612
      由 Wei Yang 提交于 
      commit 8b09549c2bfd9f3f8f4cdad74107ef4f4ff9cdd7 upstream.

Commit fa5e084e ("vmscan: do not unconditionally treat zones that
fail zone_reclaim() as full") changed the return value of
node_reclaim().  The original return value 0 means NODE_RECLAIM_SOME
after this commit.

While the return value of node_reclaim() when CONFIG_NUMA is n is not
changed.  This will leads to call zone_watermark_ok() again.

This patch fixes the return value by adjusting to NODE_RECLAIM_NOSCAN.
Since node_reclaim() is only called in page_alloc.c, move it to
mm/internal.h.

Link: http://lkml.kernel.org/r/20181113080436.22078-1-richard.weiyang@gmail.comSigned-off-by: NHui Zhu <teawaterz@linux.alibaba.com>
Signed-off-by: NWei Yang <richard.weiyang@gmail.com>
Acked-by: NMichal Hocko <mhocko@suse.com>
Reviewed-by: NMatthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: NXunlei Pang <xlpang@linux.alibaba.com>
Reviewed-by: NYang Shi <yang.shi@linux.alibaba.com>
      e431b612
  5. 07 11月, 2019 6 次提交
  7. 30 10月, 2019 5 次提交