This is a note to let you know that I've just added the patch titled mm, THP, swap: fix allocating cluster for swapfile by mistake to the 5.8-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: mm-thp-swap-fix-allocating-cluster-for-swapfile-by-mistake.patch and it can be found in the queue-5.8 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 41663430588c737dd735bad5a0d1ba325dcabd59 Mon Sep 17 00:00:00 2001 From: Gao Xiang <hsiangkao@xxxxxxxxxx> Date: Fri, 25 Sep 2020 21:19:01 -0700 Subject: mm, THP, swap: fix allocating cluster for swapfile by mistake From: Gao Xiang <hsiangkao@xxxxxxxxxx> commit 41663430588c737dd735bad5a0d1ba325dcabd59 upstream. 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: f0eea189e8e9 ("mm, THP, swap: Don't allocate huge cluster for file backed swap device") Fixes: 38d8b4e6bdc8 ("mm, THP, swap: delay splitting THP during swap out") Signed-off-by: Gao Xiang <hsiangkao@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Reviewed-by: "Huang, Ying" <ying.huang@xxxxxxxxx> Reviewed-by: Yang Shi <shy828301@xxxxxxxxx> Acked-by: Rafael Aquini <aquini@xxxxxxxxxx> Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx> Cc: Carlos Maiolino <cmaiolino@xxxxxxxxxx> Cc: Eric Sandeen <esandeen@xxxxxxxxxx> Cc: Dave Chinner <david@xxxxxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Link: https://lkml.kernel.org/r/20200820045323.7809-1-hsiangkao@xxxxxxxxxx Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- mm/swapfile.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -1074,7 +1074,7 @@ start_over: goto nextsi; } if (size == SWAPFILE_CLUSTER) { - if (!(si->flags & SWP_FS)) + if (si->flags & SWP_BLKDEV) n_ret = swap_alloc_cluster(si, swp_entries); } else n_ret = scan_swap_map_slots(si, SWAP_HAS_CACHE, Patches currently in stable-queue which might be from hsiangkao@xxxxxxxxxx are queue-5.8/mm-thp-swap-fix-allocating-cluster-for-swapfile-by-mistake.patch