BUG: KCSAN: data-race in dec_zone_page_state / write_cache_pages

[Naresh Kamboju]

LKFT started testing KCSAN enabled kernel from the linux next tree.
Here we have found BUG: KCSAN: data-race in dec_zone_page_state /
write_cache_pages

This report is from an x86_64 machine clang-11 linux next 20201201.
Since we are running for the first time we do not call this regression.

[   45.484972] BUG: KCSAN: data-race in dec_zone_page_state / write_cache_pages
[   45.492030]
[   45.493532] read-write (marked) to 0xffffd4e284455380 of 8 bytes by
task 269 on cpu 0:
[   45.501453]  write_cache_pages+0x270/0x6a0
[   45.505560]  generic_writepages+0x63/0xa0
[   45.509582]  blkdev_writepages+0xe/0x10
[   45.513429]  do_writepages+0x79/0x140
[   45.517096]  __writeback_single_inode+0x6d/0x390
[   45.521714]  writeback_sb_inodes+0x4fd/0xbe0
[   45.525986]  wb_writeback+0x42e/0x690
[   45.529652]  wb_do_writeback+0x4d2/0x530
[   45.533578]  wb_workfn+0xc8/0x4a0
[   45.536897]  process_one_work+0x4a6/0x830
[   45.540908]  worker_thread+0x5f7/0xaa0
[   45.544661]  kthread+0x20b/0x220
[   45.547893]  ret_from_fork+0x22/0x30
[   45.551471]
[   45.552963] read to 0xffffd4e284455380 of 8 bytes by task 499 on cpu 2:
[   45.559576]  dec_zone_page_state+0x1d/0x140
[   45.563764]  clear_page_dirty_for_io+0x2ab/0x3a0
[   45.568382]  write_cache_pages+0x388/0x6a0
[   45.572480]  generic_writepages+0x63/0xa0
[   45.576495]  blkdev_writepages+0xe/0x10
[   45.580334]  do_writepages+0x79/0x140
[   45.584000]  __filemap_fdatawrite_range+0x155/0x190
[   45.588880]  file_write_and_wait_range+0x51/0xa0
[   45.593498]  blkdev_fsync+0x45/0x70
[   45.596991]  __x64_sys_fsync+0xda/0x120
[   45.600830]  do_syscall_64+0x3b/0x50
[   45.604409]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
[   45.609460]
[   45.610950] Reported by Kernel Concurrency Sanitizer on:
[   45.616259] CPU: 2 PID: 499 Comm: mkfs.ext4 Not tainted
5.10.0-rc6-next-20201201 #2
[   45.623908] Hardware name: Supermicro SYS-5019S-ML/X11SSH-F, BIOS
2.2 05/23/2018

metadata:
    git_repo: https://gitlab.com/aroxell/lkft-linux-next
    target_arch: x86
    toolchain: clang-11
    git_describe: next-20201201
    download_url: https://builds.tuxbuild.com/1l8eiWgGMi6W4aDobjAAlOleFVl/

Full test log link,
https://lkft.validation.linaro.org/scheduler/job/2002643#L1866

-- 
Linaro LKFT
https://lkft.linaro.org