syzbot

BUG: Bad rss-counter state mm:ffff888023ee8c40 type:MM_SHMEMPAGES val:1 Comm:syz.2.862 Pid:9413
page: refcount:3 mapcount:1 mapping:ffff88802c4f3760 index:0x0 pfn:0x46386
memcg:ffff88801defea00
aops:shmem_aops ino:5cf
flags: 0xfff60000020029(locked|uptodate|lru|swapbacked|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff60000020029 ffffea0001629288 ffff88801e2d4490 ffff88802c4f3760
raw: 0000000000000000 0000000000000000 0000000300000000 ffff88801defea00
page dumped because: VM_BUG_ON_FOLIO(folio_mapped(folio))
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Movable, gfp_mask 0x140cca(GFP_HIGHUSER_MOVABLE|__GFP_COMP), pid 9412, tgid 9412 (syz.2.862), ts 331056939416, free_ts 321479312939
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1e1/0x250 mm/page_alloc.c:1884
 prep_new_page mm/page_alloc.c:1892 [inline]
 get_page_from_freelist+0x111d/0x3140 mm/page_alloc.c:3950
 __alloc_frozen_pages_noprof+0x26c/0x2410 mm/page_alloc.c:5245
 alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2486
 folio_alloc_mpol_noprof+0x36/0x340 mm/mempolicy.c:2505
 shmem_alloc_folio+0x135/0x160 mm/shmem.c:1919
 shmem_alloc_and_add_folio+0x371/0xd40 mm/shmem.c:1961
 shmem_get_folio_gfp+0x6ab/0x1900 mm/shmem.c:2585
 shmem_fault+0x1f9/0xa20 mm/shmem.c:2786
 __do_fault+0x10d/0x550 mm/memory.c:5323
 do_read_fault mm/memory.c:5758 [inline]
 do_fault+0xaf9/0x1990 mm/memory.c:5892
 do_pte_missing mm/memory.c:4404 [inline]
 handle_pte_fault mm/memory.c:6276 [inline]
 __handle_mm_fault+0x1807/0x2b50 mm/memory.c:6414
 handle_mm_fault+0x36d/0xa20 mm/memory.c:6583
 do_user_addr_fault+0x74c/0x12f0 arch/x86/mm/fault.c:1385
 handle_page_fault arch/x86/mm/fault.c:1474 [inline]
 exc_page_fault+0x6f/0xd0 arch/x86/mm/fault.c:1527
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618
page last free pid 9187 tgid 9187 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1433 [inline]
 free_unref_folios+0xb2a/0x1760 mm/page_alloc.c:3035
 folios_put_refs+0x53c/0x840 mm/swap.c:1002
 folio_batch_release include/linux/pagevec.h:101 [inline]
 shmem_undo_range+0x5e5/0x1570 mm/shmem.c:1150
 shmem_truncate_range mm/shmem.c:1278 [inline]
 shmem_evict_inode+0x39e/0xbd0 mm/shmem.c:1408
 evict+0x3c2/0xad0 fs/inode.c:837
 iput_final fs/inode.c:1957 [inline]
 iput.part.0+0x605/0xf50 fs/inode.c:2006
 iput+0x35/0x40 fs/inode.c:1972
 dentry_unlink_inode+0x2a1/0x490 fs/dcache.c:467
 __dentry_kill+0x1d0/0x600 fs/dcache.c:670
 finish_dput+0x76/0x480 fs/dcache.c:879
 dput.part.0+0x456/0x570 fs/dcache.c:928
 dput+0x1f/0x30 fs/dcache.c:920
 __fput+0x519/0xb40 fs/file_table.c:477
 task_work_run+0x150/0x240 kernel/task_work.c:233
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0x829/0x2a30 kernel/exit.c:971
 do_group_exit+0xd5/0x2a0 kernel/exit.c:1112
------------[ cut here ]------------
kernel BUG at mm/filemap.c:155!
Oops: invalid opcode: 0000 [#1] SMP KASAN PTI
CPU: 0 UID: 0 PID: 9413 Comm: syz.2.862 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
RIP: 0010:filemap_unaccount_folio+0x728/0xb30 mm/filemap.c:155
Code: 00 48 8b b5 a0 01 00 00 48 89 df e8 b2 7d 03 00 e9 3c fd ff ff e8 38 3e c7 ff 48 c7 c6 80 24 9d 8b 48 89 df e8 09 99 12 00 90 <0f> 0b e8 21 3e c7 ff 48 c7 c6 20 1f 9d 8b 48 89 df e8 f2 98 12 00
RSP: 0018:ffffc900045c7208 EFLAGS: 00010093
RAX: 0000000000000000 RBX: ffffea000118e180 RCX: ffffc900045c70ec
RDX: ffff888027800000 RSI: ffffffff8251c868 RDI: ffff888027800484
RBP: ffffea000118e1b0 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000001 R12: ffff88802c4f3760
R13: ffffea000118e188 R14: 0000000000000001 R15: ffffea000118e198
FS:  0000000000000000(0000) GS:ffff8881245a5000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b307bfff8 CR3: 000000003287a000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 __filemap_remove_folio+0xae/0x660 mm/filemap.c:227
 filemap_remove_folio+0xfc/0x270 mm/filemap.c:257
 truncate_inode_folio+0x49/0x70 mm/truncate.c:176
 shmem_undo_range+0x3ae/0x1570 mm/shmem.c:1146
 shmem_truncate_range mm/shmem.c:1278 [inline]
 shmem_evict_inode+0x39e/0xbd0 mm/shmem.c:1408
 evict+0x3c2/0xad0 fs/inode.c:837
 iput_final fs/inode.c:1957 [inline]
 iput.part.0+0x605/0xf50 fs/inode.c:2006
 iput+0x35/0x40 fs/inode.c:1972
 dentry_unlink_inode+0x2a1/0x490 fs/dcache.c:467
 __dentry_kill+0x1d0/0x600 fs/dcache.c:670
 finish_dput+0x76/0x480 fs/dcache.c:879
 dput.part.0+0x456/0x570 fs/dcache.c:928
 dput+0x1f/0x30 fs/dcache.c:920
 __fput+0x519/0xb40 fs/file_table.c:477
 task_work_run+0x150/0x240 kernel/task_work.c:233
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0x829/0x2a30 kernel/exit.c:971
 do_group_exit+0xd5/0x2a0 kernel/exit.c:1112
 get_signal+0x1ec7/0x21e0 kernel/signal.c:3034
 arch_do_signal_or_restart+0x91/0x770 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:64 [inline]
 exit_to_user_mode_loop+0x86/0x4a0 kernel/entry/common.c:98
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:325 [inline]
 do_syscall_64+0x668/0xf80 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fc13e99bf79
Code: Unable to access opcode bytes at 0x7fc13e99bf4f.
RSP: 002b:00007fc13f8df0e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 00007fc13ec15fa8 RCX: 00007fc13e99bf79
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007fc13ec15fa8
RBP: 00007fc13ec15fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fc13ec16038 R14: 00007ffd8be40050 R15: 00007ffd8be40138
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:filemap_unaccount_folio+0x728/0xb30 mm/filemap.c:155
Code: 00 48 8b b5 a0 01 00 00 48 89 df e8 b2 7d 03 00 e9 3c fd ff ff e8 38 3e c7 ff 48 c7 c6 80 24 9d 8b 48 89 df e8 09 99 12 00 90 <0f> 0b e8 21 3e c7 ff 48 c7 c6 20 1f 9d 8b 48 89 df e8 f2 98 12 00
RSP: 0018:ffffc900045c7208 EFLAGS: 00010093
RAX: 0000000000000000 RBX: ffffea000118e180 RCX: ffffc900045c70ec
RDX: ffff888027800000 RSI: ffffffff8251c868 RDI: ffff888027800484
RBP: ffffea000118e1b0 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000001 R12: ffff88802c4f3760
R13: ffffea000118e188 R14: 0000000000000001 R15: ffffea000118e198
FS:  0000000000000000(0000) GS:ffff8881245a5000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b307bfff8 CR3: 000000003287a000 CR4: 00000000003526f0