====================================================== WARNING: possible circular locking dependency detected 5.7.0-rc2-syzkaller #0 Not tainted ------------------------------------------------------ khugepaged/1148 is trying to acquire lock: ffff88804570d0b0 (&sb->s_type->i_mutex_key#16){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:797 [inline] ffff88804570d0b0 (&sb->s_type->i_mutex_key#16){+.+.}-{3:3}, at: shmem_fallocate+0x153/0xd40 mm/shmem.c:2734 but task is already holding lock: ffffffff89a65b60 (fs_reclaim){+.+.}-{0:0}, at: fs_reclaim_acquire.part.0+0x0/0x30 include/linux/uaccess.h:173 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (fs_reclaim){+.+.}-{0:0}: __fs_reclaim_acquire mm/page_alloc.c:4142 [inline] fs_reclaim_acquire.part.0+0x20/0x30 mm/page_alloc.c:4153 fs_reclaim_acquire mm/page_alloc.c:4742 [inline] prepare_alloc_pages mm/page_alloc.c:4739 [inline] __alloc_pages_nodemask+0x4da/0x810 mm/page_alloc.c:4791 alloc_pages_vma+0xd9/0x600 mm/mempolicy.c:2258 shmem_alloc_page+0xb0/0x170 mm/shmem.c:1486 shmem_alloc_and_acct_page+0x160/0x980 mm/shmem.c:1511 shmem_getpage_gfp+0x502/0x2a10 mm/shmem.c:1828 shmem_getpage mm/shmem.c:154 [inline] shmem_write_begin+0x102/0x1e0 mm/shmem.c:2486 generic_perform_write+0x20a/0x4e0 mm/filemap.c:3302 __generic_file_write_iter+0x24c/0x610 mm/filemap.c:3431 generic_file_write_iter+0x3f3/0x630 mm/filemap.c:3463 call_write_iter include/linux/fs.h:1907 [inline] new_sync_write+0x4a2/0x700 fs/read_write.c:484 __vfs_write+0xc9/0x100 fs/read_write.c:497 vfs_write+0x268/0x5d0 fs/read_write.c:559 ksys_write+0x12d/0x250 fs/read_write.c:612 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295 entry_SYSCALL_64_after_hwframe+0x49/0xb3 -> #0 (&sb->s_type->i_mutex_key#16){+.+.}-{3:3}: check_prev_add kernel/locking/lockdep.c:2515 [inline] check_prevs_add kernel/locking/lockdep.c:2620 [inline] validate_chain kernel/locking/lockdep.c:3237 [inline] __lock_acquire+0x2ab1/0x4c50 kernel/locking/lockdep.c:4355 lock_acquire+0x1f2/0x8f0 kernel/locking/lockdep.c:4934 down_write+0x8d/0x150 kernel/locking/rwsem.c:1531 inode_lock include/linux/fs.h:797 [inline] shmem_fallocate+0x153/0xd40 mm/shmem.c:2734 ashmem_shrink_scan drivers/staging/android/ashmem.c:490 [inline] ashmem_shrink_scan+0x34d/0x500 drivers/staging/android/ashmem.c:465 do_shrink_slab+0x3fa/0xa30 mm/vmscan.c:512 shrink_slab mm/vmscan.c:673 [inline] shrink_slab+0x16f/0x5f0 mm/vmscan.c:646 shrink_node_memcgs mm/vmscan.c:2673 [inline] shrink_node+0x477/0x1b20 mm/vmscan.c:2777 shrink_zones mm/vmscan.c:2980 [inline] do_try_to_free_pages+0x38d/0x13a0 mm/vmscan.c:3033 try_to_free_pages+0x293/0x8d0 mm/vmscan.c:3272 __perform_reclaim mm/page_alloc.c:4182 [inline] __alloc_pages_direct_reclaim mm/page_alloc.c:4203 [inline] __alloc_pages_slowpath.constprop.0+0x903/0x2660 mm/page_alloc.c:4609 __alloc_pages_nodemask+0x5d9/0x810 mm/page_alloc.c:4822 __alloc_pages include/linux/gfp.h:504 [inline] __alloc_pages_node include/linux/gfp.h:517 [inline] khugepaged_alloc_page+0xa0/0x170 mm/khugepaged.c:782 collapse_huge_page+0x129/0x4040 mm/khugepaged.c:971 khugepaged_scan_pmd mm/khugepaged.c:1251 [inline] khugepaged_scan_mm_slot mm/khugepaged.c:2019 [inline] khugepaged_do_scan mm/khugepaged.c:2100 [inline] khugepaged+0x334b/0x4370 mm/khugepaged.c:2145 kthread+0x388/0x470 kernel/kthread.c:268 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(fs_reclaim); lock(&sb->s_type->i_mutex_key#16); lock(fs_reclaim); lock(&sb->s_type->i_mutex_key#16); *** DEADLOCK *** 2 locks held by khugepaged/1148: #0: ffffffff89a65b60 (fs_reclaim){+.+.}-{0:0}, at: fs_reclaim_acquire.part.0+0x0/0x30 include/linux/uaccess.h:173 #1: ffffffff89a404b0 (shrinker_rwsem){++++}-{3:3}, at: shrink_slab mm/vmscan.c:663 [inline] #1: ffffffff89a404b0 (shrinker_rwsem){++++}-{3:3}, at: shrink_slab+0xc7/0x5f0 mm/vmscan.c:646 stack backtrace: CPU: 1 PID: 1148 Comm: khugepaged Not tainted 5.7.0-rc2-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x188/0x20d lib/dump_stack.c:118 check_noncircular+0x32e/0x3e0 kernel/locking/lockdep.c:1846 check_prev_add kernel/locking/lockdep.c:2515 [inline] check_prevs_add kernel/locking/lockdep.c:2620 [inline] validate_chain kernel/locking/lockdep.c:3237 [inline] __lock_acquire+0x2ab1/0x4c50 kernel/locking/lockdep.c:4355 lock_acquire+0x1f2/0x8f0 kernel/locking/lockdep.c:4934 down_write+0x8d/0x150 kernel/locking/rwsem.c:1531 inode_lock include/linux/fs.h:797 [inline] shmem_fallocate+0x153/0xd40 mm/shmem.c:2734 ashmem_shrink_scan drivers/staging/android/ashmem.c:490 [inline] ashmem_shrink_scan+0x34d/0x500 drivers/staging/android/ashmem.c:465 do_shrink_slab+0x3fa/0xa30 mm/vmscan.c:512 shrink_slab mm/vmscan.c:673 [inline] shrink_slab+0x16f/0x5f0 mm/vmscan.c:646 shrink_node_memcgs mm/vmscan.c:2673 [inline] shrink_node+0x477/0x1b20 mm/vmscan.c:2777 shrink_zones mm/vmscan.c:2980 [inline] do_try_to_free_pages+0x38d/0x13a0 mm/vmscan.c:3033 try_to_free_pages+0x293/0x8d0 mm/vmscan.c:3272 __perform_reclaim mm/page_alloc.c:4182 [inline] __alloc_pages_direct_reclaim mm/page_alloc.c:4203 [inline] __alloc_pages_slowpath.constprop.0+0x903/0x2660 mm/page_alloc.c:4609 __alloc_pages_nodemask+0x5d9/0x810 mm/page_alloc.c:4822 __alloc_pages include/linux/gfp.h:504 [inline] __alloc_pages_node include/linux/gfp.h:517 [inline] khugepaged_alloc_page+0xa0/0x170 mm/khugepaged.c:782 collapse_huge_page+0x129/0x4040 mm/khugepaged.c:971 khugepaged_scan_pmd mm/khugepaged.c:1251 [inline] khugepaged_scan_mm_slot mm/khugepaged.c:2019 [inline] khugepaged_do_scan mm/khugepaged.c:2100 [inline] khugepaged+0x334b/0x4370 mm/khugepaged.c:2145 kthread+0x388/0x470 kernel/kthread.c:268 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352