On Thu, 10 Oct 2024 01:44:27 -0700 syzbot <syzbot+febb2473441bfb8fb380@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > Hello, > > syzbot found the following issue on: > > HEAD commit: fc20a3e57247 Merge tag 'for-linus-6.12a-rc2-tag' of git://.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=11cdfd27980000 > kernel config: https://syzkaller.appspot.com/x/.config?x=d302f14701986aa0 > dashboard link: https://syzkaller.appspot.com/bug?extid=febb2473441bfb8fb380 > compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40 > > Unfortunately, I don't have any reproducer for this issue yet. > > Downloadable assets: > disk image: https://storage.googleapis.com/syzbot-assets/5b4b9aca7b75/disk-fc20a3e5.raw.xz > vmlinux: https://storage.googleapis.com/syzbot-assets/b22e17636ec0/vmlinux-fc20a3e5.xz > kernel image: https://storage.googleapis.com/syzbot-assets/5266e625be99/bzImage-fc20a3e5.xz > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+febb2473441bfb8fb380@xxxxxxxxxxxxxxxxxxxxxxxxx Thanks. I'm guessing that shmem symlinks aren't initializing the whole page (folio) and that has tripped up Usama's "store zero pages to be swapped out in a bitmap" feature - it's checking the uninitialized part of the page for zeroness. > ===================================================== > BUG: KMSAN: uninit-value in is_folio_zero_filled mm/page_io.c:189 [inline] > BUG: KMSAN: uninit-value in swap_writepage+0x536/0x12b0 mm/page_io.c:259 > is_folio_zero_filled mm/page_io.c:189 [inline] > swap_writepage+0x536/0x12b0 mm/page_io.c:259 > shmem_writepage+0x2117/0x2450 mm/shmem.c:1567 > pageout mm/vmscan.c:688 [inline] > shrink_folio_list+0x5e78/0x7dd0 mm/vmscan.c:1366 > evict_folios+0x9813/0xbaf0 mm/vmscan.c:4583 > try_to_shrink_lruvec+0x13a3/0x1750 mm/vmscan.c:4778 > shrink_one+0x646/0xd20 mm/vmscan.c:4816 > shrink_many mm/vmscan.c:4879 [inline] > lru_gen_shrink_node mm/vmscan.c:4957 [inline] > shrink_node+0x451a/0x50f0 mm/vmscan.c:5937 > kswapd_shrink_node mm/vmscan.c:6765 [inline] > balance_pgdat mm/vmscan.c:6957 [inline] > kswapd+0x25e2/0x42f0 mm/vmscan.c:7226 > kthread+0x3e2/0x540 kernel/kthread.c:389 > ret_from_fork+0x6d/0x90 arch/x86/kernel/process.c:147 > ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 > > Uninit was created at: > __alloc_pages_noprof+0x9d6/0xe70 mm/page_alloc.c:4756 > alloc_pages_mpol_noprof+0x299/0x990 mm/mempolicy.c:2265 > folio_alloc_mpol_noprof+0x55/0x180 mm/mempolicy.c:2283 > shmem_alloc_folio mm/shmem.c:1774 [inline] > shmem_alloc_and_add_folio+0xc33/0x1c30 mm/shmem.c:1813 > shmem_get_folio_gfp+0xacd/0x1f30 mm/shmem.c:2335 > shmem_get_folio mm/shmem.c:2441 [inline] > shmem_symlink+0x528/0xa20 mm/shmem.c:3834 > vfs_symlink+0x1ed/0x460 fs/namei.c:4615 > do_symlinkat+0x257/0x8a0 fs/namei.c:4641 > __do_sys_symlink fs/namei.c:4662 [inline] > __se_sys_symlink fs/namei.c:4660 [inline] > __x64_sys_symlink+0xe0/0x140 fs/namei.c:4660 > x64_sys_call+0x30e8/0x3ba0 arch/x86/include/generated/asm/syscalls_64.h:89 > do_syscall_x64 arch/x86/entry/common.c:52 [inline] > do_syscall_64+0xcd/0x1e0 arch/x86/entry/common.c:83 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > CPU: 1 UID: 0 PID: 80 Comm: kswapd0 Tainted: G W 6.12.0-rc1-syzkaller-00330-gfc20a3e57247 #0 > Tainted: [W]=WARN > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024 > ===================================================== > > > --- > This report is generated by a bot. It may contain errors. > See https://goo.gl/tpsmEJ for more information about syzbot. > syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx. > > syzbot will keep track of this issue. See: > https://goo.gl/tpsmEJ#status for how to communicate with syzbot. > > If the report is already addressed, let syzbot know by replying with: > #syz fix: exact-commit-title > > If you want to overwrite report's subsystems, reply with: > #syz set subsystems: new-subsystem > (See the list of subsystem names on the web dashboard) > > If the report is a duplicate of another one, reply with: > #syz dup: exact-subject-of-another-report > > If you want to undo deduplication, reply with: > #syz undup
