1. 27 9月, 2020 1 次提交
    • G
      mm, THP, swap: fix allocating cluster for swapfile by mistake · 41663430
      Gao Xiang 提交于
      SWP_FS is used to make swap_{read,write}page() go through the
      filesystem, and it's only used for swap files over NFS.  So, !SWP_FS
      means non NFS for now, it could be either file backed or device backed.
      Something similar goes with legacy SWP_FILE.
      
      So in order to achieve the goal of the original patch, SWP_BLKDEV should
      be used instead.
      
      FS corruption can be observed with SSD device + XFS + fragmented
      swapfile due to CONFIG_THP_SWAP=y.
      
      I reproduced the issue with the following details:
      
      Environment:
      
        QEMU + upstream kernel + buildroot + NVMe (2 GB)
      
      Kernel config:
      
        CONFIG_BLK_DEV_NVME=y
        CONFIG_THP_SWAP=y
      
      Some reproducible steps:
      
        mkfs.xfs -f /dev/nvme0n1
        mkdir /tmp/mnt
        mount /dev/nvme0n1 /tmp/mnt
        bs="32k"
        sz="1024m"    # doesn't matter too much, I also tried 16m
        xfs_io -f -c "pwrite -R -b $bs 0 $sz" -c "fdatasync" /tmp/mnt/sw
        xfs_io -f -c "pwrite -R -b $bs 0 $sz" -c "fdatasync" /tmp/mnt/sw
        xfs_io -f -c "pwrite -R -b $bs 0 $sz" -c "fdatasync" /tmp/mnt/sw
        xfs_io -f -c "pwrite -F -S 0 -b $bs 0 $sz" -c "fdatasync" /tmp/mnt/sw
        xfs_io -f -c "pwrite -R -b $bs 0 $sz" -c "fsync" /tmp/mnt/sw
      
        mkswap /tmp/mnt/sw
        swapon /tmp/mnt/sw
      
        stress --vm 2 --vm-bytes 600M   # doesn't matter too much as well
      
      Symptoms:
       - FS corruption (e.g. checksum failure)
       - memory corruption at: 0xd2808010
       - segfault
      
      Fixes: f0eea189 ("mm, THP, swap: Don't allocate huge cluster for file backed swap device")
      Fixes: 38d8b4e6 ("mm, THP, swap: delay splitting THP during swap out")
      Signed-off-by: NGao Xiang <hsiangkao@redhat.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Reviewed-by: N"Huang, Ying" <ying.huang@intel.com>
      Reviewed-by: NYang Shi <shy828301@gmail.com>
      Acked-by: NRafael Aquini <aquini@redhat.com>
      Cc: Matthew Wilcox <willy@infradead.org>
      Cc: Carlos Maiolino <cmaiolino@redhat.com>
      Cc: Eric Sandeen <esandeen@redhat.com>
      Cc: Dave Chinner <david@fromorbit.com>
      Cc: <stable@vger.kernel.org>
      Link: https://lkml.kernel.org/r/20200820045323.7809-1-hsiangkao@redhat.comSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      41663430
  2. 26 9月, 2020 11 次提交
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