* [RFC] DEPT report on around ntfs3 and filemap
@ 2025-06-23 2:31 Byungchul Park
0 siblings, 0 replies; only message in thread
From: Byungchul Park @ 2025-06-23 2:31 UTC (permalink / raw)
To: linux-kernel, almaz.alexandrovich, ntfs3
Cc: kernel_team, torvalds, akpm, yeoreum.yun, yunseong.kim,
gwan-gyeong.mun, harry.yoo, ysk
Hi folks,
Thanks to Yunseong, we got a DEPT report in ntfs3. It doesn't mean it's
an obvious deadlock, but after digging into the report, I'm wondering if
it could happen by any chance. The scenario that I'm concerning is:
CONTEXT A CONTEXT B
ntfs_fill_super()
inode_read_data() // for sbi->def_table and sbi->upcase
... ntfs_lookup()
mutex_lock(&ni->ni_lock) // hold
dir_search_u()
...
btfs_bread()
folio_lock() // hold
filemap_read_folio() // with folio lock held
...
__find_get_block_slow()
folio_lock() // stuck
ntfs_read_folio()
mutex_lock(&ni->ni_lock) // stuck
Am I missing something? One thing possibily I'm missing is that the two
ni_locks never contend, but I'm not sure if it's true for the all
possible cases e.g. manipulating block dev directly.
FYI, the following is the DEPT report we got.
Byungchul
---
[ 2279.669417][T42160] ===================================================
[ 2279.669468][T42160] DEPT: Circular dependency has been detected.
[ 2279.669483][T42160] 6.15.0-rc6-00043-ga83a69ec7f9f #5 Not tainted
[ 2279.669499][T42160] ---------------------------------------------------
[ 2279.669511][T42160] summary
[ 2279.669522][T42160] ---------------------------------------------------
[ 2279.669534][T42160] *** DEADLOCK ***
[ 2279.669534][T42160]
[ 2279.669545][T42160] context A
[ 2279.669557][T42160] [S] (unknown)(pg_locked_map:0)
[ 2279.669572][T42160] [W] lock(&ni->ni_lock:0)
[ 2279.669587][T42160] [E] dept_page_clear_bit(pg_locked_map:0)
[ 2279.669601][T42160]
[ 2279.669611][T42160] context B
[ 2279.669622][T42160] [S] lock(&ni->ni_lock:0)
[ 2279.669635][T42160] [W] dept_page_wait_on_bit(pg_locked_map:0)
[ 2279.669650][T42160] [E] unlock(&ni->ni_lock:0)
[ 2279.669663][T42160]
[ 2279.669673][T42160] [S]: start of the event context
[ 2279.669683][T42160] [W]: the wait blocked
[ 2279.669693][T42160] [E]: the event not reachable
[ 2279.669704][T42160] ---------------------------------------------------
[ 2279.669714][T42160] context A's detail
[ 2279.669725][T42160] ---------------------------------------------------
[ 2279.669735][T42160] context A
[ 2279.669746][T42160] [S] (unknown)(pg_locked_map:0)
[ 2279.669759][T42160] [W] lock(&ni->ni_lock:0)
[ 2279.669772][T42160] [E] dept_page_clear_bit(pg_locked_map:0)
[ 2279.669786][T42160]
[ 2279.669796][T42160] [S] (unknown)(pg_locked_map:0):
[ 2279.669809][T42160] (N/A)
[ 2279.669818][T42160]
[ 2279.669828][T42160] [W] lock(&ni->ni_lock:0):
[ 2279.669841][T42160] [<ffff800081935bd4>] ntfs_read_folio+0x174/0x200
[ 2279.669875][T42160] stacktrace:
[ 2279.669901][T42160] __mutex_lock+0x730/0xa08
[ 2279.669932][T42160] mutex_lock_nested+0x24/0x38
[ 2279.669952][T42160] ntfs_read_folio+0x174/0x200
[ 2279.669970][T42160] filemap_read_folio+0xc8/0x280
[ 2279.669990][T42160] do_read_cache_folio+0x290/0x56c
[ 2279.670010][T42160] read_cache_page+0x64/0x150
[ 2279.670027][T42160] inode_read_data+0xa4/0x9c0
[ 2279.670046][T42160] ntfs_fill_super+0x1fec/0x3840
[ 2279.670072][T42160] get_tree_bdev_flags+0x330/0x528
[ 2279.670099][T42160] get_tree_bdev+0x2c/0x3c
[ 2279.670119][T42160] ntfs_fs_get_tree+0x28/0x38
[ 2279.670139][T42160] vfs_get_tree+0x7c/0x2c0
[ 2279.670158][T42160] path_mount+0x1380/0x1d20
[ 2279.670184][T42160] __arm64_sys_mount+0x438/0x530
[ 2279.670204][T42160] invoke_syscall+0x88/0x2e0
[ 2279.670234][T42160] el0_svc_common.constprop.0+0xe8/0x2e0
[ 2279.670256][T42160]
[ 2279.670265][T42160] [E] dept_page_clear_bit(pg_locked_map:0):
[ 2279.670279][T42160] [<ffff800081935c14>] ntfs_read_folio+0x1b4/0x200
[ 2279.670299][T42160] stacktrace:
[ 2279.670309][T42160] ntfs_read_folio+0x1b4/0x200
[ 2279.670327][T42160] filemap_read_folio+0xc8/0x280
[ 2279.670343][T42160] do_read_cache_folio+0x290/0x56c
[ 2279.670361][T42160] read_cache_page+0x64/0x150
[ 2279.670378][T42160] inode_read_data+0xa4/0x9c0
[ 2279.670396][T42160] ntfs_fill_super+0x1fec/0x3840
[ 2279.670418][T42160] get_tree_bdev_flags+0x330/0x528
[ 2279.670438][T42160] get_tree_bdev+0x2c/0x3c
[ 2279.670458][T42160] ntfs_fs_get_tree+0x28/0x38
[ 2279.670478][T42160] vfs_get_tree+0x7c/0x2c0
[ 2279.670497][T42160] path_mount+0x1380/0x1d20
[ 2279.670516][T42160] __arm64_sys_mount+0x438/0x530
[ 2279.670535][T42160] invoke_syscall+0x88/0x2e0
[ 2279.670555][T42160] el0_svc_common.constprop.0+0xe8/0x2e0
[ 2279.670577][T42160] do_el0_svc+0x44/0x60
[ 2279.670597][T42160] el0_svc+0x50/0x188
[ 2279.670626][T42160] ---------------------------------------------------
[ 2279.670637][T42160] context B's detail
[ 2279.670648][T42160] ---------------------------------------------------
[ 2279.670659][T42160] context B
[ 2279.670669][T42160] [S] lock(&ni->ni_lock:0)
[ 2279.670683][T42160] [W] dept_page_wait_on_bit(pg_locked_map:0)
[ 2279.670697][T42160] [E] unlock(&ni->ni_lock:0)
[ 2279.670710][T42160]
[ 2279.670719][T42160] [S] lock(&ni->ni_lock:0):
[ 2279.670732][T42160] [<ffff800081951e78>] ntfs_lookup+0x188/0x238
[ 2279.670755][T42160] stacktrace:
[ 2279.670764][T42160] __mutex_lock+0x74c/0xa08
[ 2279.670783][T42160] mutex_lock_nested+0x24/0x38
[ 2279.670803][T42160] ntfs_lookup+0x188/0x238
[ 2279.670822][T42160] lookup_open.isra.0+0x414/0x1310
[ 2279.670846][T42160] path_openat+0x1174/0x2740
[ 2279.670867][T42160] do_filp_open+0x198/0x3a0
[ 2279.670895][T42160] do_sys_openat2+0x11c/0x1e0
[ 2279.670912][T42160] __arm64_sys_openat+0x158/0x208
[ 2279.670929][T42160] invoke_syscall+0x88/0x2e0
[ 2279.670949][T42160] el0_svc_common.constprop.0+0xe8/0x2e0
[ 2279.670970][T42160] do_el0_svc+0x44/0x60
[ 2279.670990][T42160] el0_svc+0x50/0x188
[ 2279.671011][T42160] el0t_64_sync_handler+0x10c/0x140
[ 2279.671034][T42160] el0t_64_sync+0x198/0x19c
[ 2279.671053][T42160]
[ 2279.671062][T42160] [W] dept_page_wait_on_bit(pg_locked_map:0):
[ 2279.671075][T42160] [<ffff800080dfcae4>] bdev_getblk+0x174/0x218
[ 2279.671100][T42160] stacktrace:
[ 2279.671110][T42160] __find_get_block_slow+0x26c/0x684
[ 2279.671128][T42160] bdev_getblk+0x174/0x218
[ 2279.671145][T42160] __bread_gfp+0x8c/0x2b8
[ 2279.671162][T42160] ntfs_bread+0xb8/0x22c
[ 2279.671192][T42160] wnd_map+0x264/0x3a0
[ 2279.671212][T42160] wnd_is_used+0x338/0x520
[ 2279.671232][T42160] run_unpack_ex+0x454/0x62c
[ 2279.671252][T42160] ntfs_iget5+0x980/0x3048
[ 2279.671270][T42160] dir_search_u+0x140/0x348
[ 2279.671290][T42160] ntfs_lookup+0x198/0x238
[ 2279.671309][T42160] lookup_open.isra.0+0x414/0x1310
[ 2279.671328][T42160] path_openat+0x1174/0x2740
[ 2279.671348][T42160] do_filp_open+0x198/0x3a0
[ 2279.671367][T42160] do_sys_openat2+0x11c/0x1e0
[ 2279.671383][T42160] __arm64_sys_openat+0x158/0x208
[ 2279.671400][T42160] invoke_syscall+0x88/0x2e0
[ 2279.671420][T42160]
[ 2279.671430][T42160] [E] unlock(&ni->ni_lock:0):
[ 2279.671442][T42160] (N/A)
[ 2279.671452][T42160] ---------------------------------------------------
[ 2279.671463][T42160] information that might be helpful
[ 2279.671473][T42160] ---------------------------------------------------
[ 2279.671488][T42160] CPU: 2 UID: 0 PID: 42160 Comm: syz.0.6499 Not tainted 6.15.0-rc6-00043-ga83a69ec7f9f #5 PREEMPT
[ 2279.671502][T42160] Hardware name: QEMU KVM Virtual Machine, BIOS 2025.02-8 05/13/2025
[ 2279.671510][T42160] Call trace:
[ 2279.671515][T42160] show_stack+0x34/0x80 (C)
[ 2279.671542][T42160] dump_stack_lvl+0x104/0x180
[ 2279.671568][T42160] dump_stack+0x20/0x2c
[ 2279.671583][T42160] cb_check_dl+0x1080/0x10ec
[ 2279.671599][T42160] bfs+0x4d8/0x630
[ 2279.671610][T42160] add_dep+0x1cc/0x364
[ 2279.671623][T42160] __dept_event.part.0+0xde0/0x1240
[ 2279.671636][T42160] dept_event+0x208/0x29c
[ 2279.671649][T42160] folio_unlock+0x8c/0x160
[ 2279.671678][T42160] ntfs_read_folio+0x1b4/0x200
[ 2279.671691][T42160] filemap_read_folio+0xc8/0x280
[ 2279.671702][T42160] do_read_cache_folio+0x290/0x56c
[ 2279.671714][T42160] read_cache_page+0x64/0x150
[ 2279.671726][T42160] inode_read_data+0xa4/0x9c0
[ 2279.671740][T42160] ntfs_fill_super+0x1fec/0x3840
[ 2279.671756][T42160] get_tree_bdev_flags+0x330/0x528
[ 2279.671771][T42160] get_tree_bdev+0x2c/0x3c
[ 2279.671786][T42160] ntfs_fs_get_tree+0x28/0x38
[ 2279.671801][T42160] vfs_get_tree+0x7c/0x2c0
[ 2279.671815][T42160] path_mount+0x1380/0x1d20
[ 2279.671829][T42160] __arm64_sys_mount+0x438/0x530
[ 2279.671844][T42160] invoke_syscall+0x88/0x2e0
[ 2279.671859][T42160] el0_svc_common.constprop.0+0xe8/0x2e0
[ 2279.671875][T42160] do_el0_svc+0x44/0x60
[ 2279.671898][T42160] el0_svc+0x50/0x188
[ 2279.671915][T42160] el0t_64_sync_handler+0x10c/0x140
[ 2279.671932][T42160] el0t_64_sync+0x198/0x19c
^ permalink raw reply [flat|nested] only message in thread
only message in thread, other threads:[~2025-06-23 2:31 UTC | newest]
Thread overview: (only message) (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2025-06-23 2:31 [RFC] DEPT report on around ntfs3 and filemap Byungchul Park
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).