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