Re: [RFC] DEPT report on around btrfs, unlink, and truncate

[Qu Wenruo]

在 2025/6/23 17:49, Byungchul Park 写道:
> On Mon, Jun 23, 2025 at 03:20:43PM +0930, Qu Wenruo wrote:
> > 在 2025/6/23 12:51, Byungchul Park 写道:
> > > Hi folks,
> > >
> > > Thanks to Yunseong, we got two DEPT reports in btrfs.  It doesn't mean
> > > it's obvious deadlocks, but after digging into the reports, I'm
> > > wondering if it could happen by any chance.
> > >
> > > 1) The first scenario that I'm concerning is:
> > >
> > >     context A            context B
> > >
> > >                          do_truncate()
> > >                            ...
> > >                              btrfs_do_readpage() // with folio lock held
> >
> >                                 This one is for data.
>
> Do you mean this folio is for data?  Thanks for the confirmation.

Yes, only data folios will go through btrfs_do_readpage().

For metadata, we never go through btrfs_do_readpage(), but 
read_extent_buffer_pages_nowait().


> > >     do_unlinkat()
> > >       ...
> > >         push_leaf_right()
> > >        btrfs_tree_lock_nested()
> > >          down_write_nested(&eb->lock) // hold
>
> This is struct extent_buffer's rw_sem.  Right?
>
> > >                                btrfs_get_extent()
> > >                                  btrfs_lookup_file_extent()
> > >                                    btrfs_search_slot()
> > >                                      down_read_nested(&eb->lock) // stuck
> >
> >                                         This one is for metadata.
> 						^
> 					I don't get this actually.
>
> This is struct extent_buffer's rw_sem, too.  Cannot this rw_sem be the
> same as the rw_sem above in context A?

My bad, I thought you're talking about that down_read_nested() 
conflicting with folio lock.

But if you're talking about extent_buffer::lock, then the one in context 
B will wait for the one in context A, and that's expected.

> > Data and metadata page cache will never cross into each other.
> >
> > Thanks,
> > Qu
> >
> > >          __push_leaf_right()
> > >            ...
> > >              folio_lock() // stuck
>
> Did you mean this folio is always for metadata?

Can you explain more on where this folio_lock() comes from?

I didn't see any location where __push_leaf_right() is locking a folio 
nor the original do_unlinkat().

So here I can only guess the folio is from __push_leaf_right() context, 
that means it can only be a metadata folio.

> If no, it could lead a deadlock in my opinion.  If yes, dept should
> assign different classes to folios between data data and metadata.

So far I believe the folio belongs to metadata.

And since btrfs has very different handling of metadata folios, and it's 
a little confusing that, we also have a btree_inode to handle the 
metadata page cache, but do not have read_folio() callbacks, it can be a 
little confusing to some automatic tools.

Thanks,
Qu

> 	Byungchul
>
> > > 2) The second scenario that I'm concerning is:
> > >
> > >     context A            context B
> > >
> > >                          do_truncate()
> > >                            ...
> > >                              btrfs_do_readpage() // with folio lock held
> > >     do_unlinkat()
> > >       ...
> > >         btrfs_truncate_inode_items()
> > >        btrfs_lock_root_node()
> > >          down_write_nested(&eb->lock) // hold
> > >        btrfs_del_items()
> > >          push_leaf_right()
> > >            __push_leaf_right()
> > >                                btrfs_get_extent()
> > >                                  btrfs_lookup_file_extent()
> > >                                    btrfs_search_slot()
> > >                                      btrfs_read_lock_root_node()
> > >                                        down_read_nested(&eb->lock) // stuck
> > >              ...
> > >                folio_lock() //stuck
> > >
> > > Am I missing something?
> > >
> > > FYI, the followings are the DEPT reports we got.
> > >
> > >        Byungchul
> > >
> > > ---
> > >    [  304.343395][ T7488] ===================================================
> > >    [  304.343446][ T7488] DEPT: Circular dependency has been detected.
> > >    [  304.343462][ T7488] 6.15.0-rc6-00043-ga83a69ec7f9f #5 Not tainted
> > >    [  304.343477][ T7488] ---------------------------------------------------
> > >    [  304.343488][ T7488] summary
> > >    [  304.343498][ T7488] ---------------------------------------------------
> > >    [  304.343509][ T7488] *** DEADLOCK ***
> > >    [  304.343509][ T7488]
> > >    [  304.343520][ T7488] context A
> > >    [  304.343531][ T7488]    [S] lock(btrfs-tree-00:0)
> > >    [  304.343545][ T7488]    [W] dept_page_wait_on_bit(pg_locked_map:0)
> > >    [  304.343559][ T7488]    [E] unlock(btrfs-tree-00:0)
> > >    [  304.343572][ T7488]
> > >    [  304.343581][ T7488] context B
> > >    [  304.343591][ T7488]    [S] (unknown)(pg_locked_map:0)
> > >    [  304.343603][ T7488]    [W] lock(btrfs-tree-00:0)
> > >    [  304.343616][ T7488]    [E] dept_page_clear_bit(pg_locked_map:0)
> > >    [  304.343629][ T7488]
> > >    [  304.343637][ T7488] [S]: start of the event context
> > >    [  304.343647][ T7488] [W]: the wait blocked
> > >    [  304.343656][ T7488] [E]: the event not reachable
> > >    [  304.343666][ T7488] ---------------------------------------------------
> > >    [  304.343676][ T7488] context A's detail
> > >    [  304.343686][ T7488] ---------------------------------------------------
> > >    [  304.343696][ T7488] context A
> > >    [  304.343706][ T7488]    [S] lock(btrfs-tree-00:0)
> > >    [  304.343718][ T7488]    [W] dept_page_wait_on_bit(pg_locked_map:0)
> > >    [  304.343731][ T7488]    [E] unlock(btrfs-tree-00:0)
> > >    [  304.343744][ T7488]
> > >    [  304.343753][ T7488] [S] lock(btrfs-tree-00:0):
> > >    [  304.343764][ T7488] [<ffff8000824f41d8>] btrfs_tree_lock_nested+0x38/0x324
> > >    [  304.343796][ T7488] stacktrace:
> > >    [  304.343805][ T7488]       down_write_nested+0xe4/0x21c
> > >    [  304.343826][ T7488]       btrfs_tree_lock_nested+0x38/0x324
> > >    [  304.343865][ T7488]       push_leaf_right+0x23c/0x628
> > >    [  304.343896][ T7488]       btrfs_del_items+0x974/0xaec
> > >    [  304.343916][ T7488]       btrfs_truncate_inode_items+0x1c5c/0x2b00
> > >    [  304.343938][ T7488]       btrfs_evict_inode+0xa4c/0xd38
> > >    [  304.343968][ T7488]       evict+0x340/0x7b0
> > >    [  304.343993][ T7488]       iput+0x4ec/0x840
> > >    [  304.344011][ T7488]       do_unlinkat+0x444/0x59c
> > >    [  304.344038][ T7488]       __arm64_sys_unlinkat+0x11c/0x260
> > >    [  304.344057][ T7488]       invoke_syscall+0x88/0x2e0
> > >    [  304.344084][ T7488]       el0_svc_common.constprop.0+0xe8/0x2e0
> > >    [  304.344104][ T7488]       do_el0_svc+0x44/0x60
> > >    [  304.344123][ T7488]       el0_svc+0x50/0x188
> > >    [  304.344151][ T7488]       el0t_64_sync_handler+0x10c/0x140
> > >    [  304.344172][ T7488]       el0t_64_sync+0x198/0x19c
> > >    [  304.344189][ T7488]
> > >    [  304.344198][ T7488] [W] dept_page_wait_on_bit(pg_locked_map:0):
> > >    [  304.344211][ T7488] [<ffff8000823b1d20>] __push_leaf_right+0x8f0/0xc70
> > >    [  304.344232][ T7488] stacktrace:
> > >    [  304.344241][ T7488]       __push_leaf_right+0x8f0/0xc70
> > >    [  304.344260][ T7488]       push_leaf_right+0x408/0x628
> > >    [  304.344278][ T7488]       btrfs_del_items+0x974/0xaec
> > >    [  304.344297][ T7488]       btrfs_truncate_inode_items+0x1c5c/0x2b00
> > >    [  304.344314][ T7488]       btrfs_evict_inode+0xa4c/0xd38
> > >    [  304.344335][ T7488]       evict+0x340/0x7b0
> > >    [  304.344352][ T7488]       iput+0x4ec/0x840
> > >    [  304.344369][ T7488]       do_unlinkat+0x444/0x59c
> > >    [  304.344388][ T7488]       __arm64_sys_unlinkat+0x11c/0x260
> > >    [  304.344407][ T7488]       invoke_syscall+0x88/0x2e0
> > >    [  304.344425][ T7488]       el0_svc_common.constprop.0+0xe8/0x2e0
> > >    [  304.344445][ T7488]       do_el0_svc+0x44/0x60
> > >    [  304.344463][ T7488]       el0_svc+0x50/0x188
> > >    [  304.344482][ T7488]       el0t_64_sync_handler+0x10c/0x140
> > >    [  304.344503][ T7488]       el0t_64_sync+0x198/0x19c
> > >    [  304.344518][ T7488]
> > >    [  304.344527][ T7488] [E] unlock(btrfs-tree-00:0):
> > >    [  304.344539][ T7488] (N/A)
> > >    [  304.344549][ T7488] ---------------------------------------------------
> > >    [  304.344559][ T7488] context B's detail
> > >    [  304.344568][ T7488] ---------------------------------------------------
> > >    [  304.344578][ T7488] context B
> > >    [  304.344588][ T7488]    [S] (unknown)(pg_locked_map:0)
> > >    [  304.344600][ T7488]    [W] lock(btrfs-tree-00:0)
> > >    [  304.344613][ T7488]    [E] dept_page_clear_bit(pg_locked_map:0)
> > >    [  304.344625][ T7488]
> > >    [  304.344634][ T7488] [S] (unknown)(pg_locked_map:0):
> > >    [  304.344646][ T7488] (N/A)
> > >    [  304.344655][ T7488]
> > >    [  304.344663][ T7488] [W] lock(btrfs-tree-00:0):
> > >    [  304.344675][ T7488] [<ffff8000824f3b48>] btrfs_tree_read_lock_nested+0x38/0x330
> > >    [  304.344694][ T7488] stacktrace:
> > >    [  304.344703][ T7488]       down_read_nested+0xc8/0x368
> > >    [  304.344720][ T7488]       btrfs_tree_read_lock_nested+0x38/0x330
> > >    [  304.344737][ T7488]       btrfs_search_slot+0x1204/0x2dc8
> > >    [  304.344756][ T7488]       btrfs_lookup_file_extent+0xe0/0x128
> > >    [  304.344773][ T7488]       btrfs_get_extent+0x2cc/0x1e24
> > >    [  304.344789][ T7488]       btrfs_do_readpage+0x628/0x1258
> > >    [  304.344810][ T7488]       btrfs_read_folio+0x310/0x450
> > >    [  304.344828][ T7488]       btrfs_truncate_block+0x2c0/0xb24
> > >    [  304.344854][ T7488]       btrfs_cont_expand+0x11c/0xba8
> > >    [  304.344870][ T7488]       btrfs_setattr+0x8d8/0x10f4
> > >    [  304.344885][ T7488]       notify_change+0x900/0xfbc
> > >    [  304.344906][ T7488]       do_truncate+0x154/0x210
> > >    [  304.344937][ T7488]       vfs_truncate+0x55c/0x66c
> > >    [  304.344957][ T7488]       __arm64_sys_truncate+0x16c/0x1e4
> > >    [  304.344978][ T7488]       invoke_syscall+0x88/0x2e0
> > >    [  304.344997][ T7488]       el0_svc_common.constprop.0+0xe8/0x2e0
> > >    [  304.345017][ T7488]
> > >    [  304.345025][ T7488] [E] dept_page_clear_bit(pg_locked_map:0):
> > >    [  304.345037][ T7488] [<ffff80008249c284>] end_folio_read+0x3e4/0x590
> > >    [  304.345056][ T7488] stacktrace:
> > >    [  304.345065][ T7488]       folio_unlock+0x8c/0x160
> > >    [  304.345099][ T7488]       end_folio_read+0x3e4/0x590
> > >    [  304.345116][ T7488]       btrfs_do_readpage+0x830/0x1258
> > >    [  304.345132][ T7488]       btrfs_read_folio+0x310/0x450
> > >    [  304.345149][ T7488]       btrfs_truncate_block+0x2c0/0xb24
> > >    [  304.345164][ T7488]       btrfs_cont_expand+0x11c/0xba8
> > >    [  304.345179][ T7488]       btrfs_setattr+0x8d8/0x10f4
> > >    [  304.345194][ T7488]       notify_change+0x900/0xfbc
> > >    [  304.345213][ T7488]       do_truncate+0x154/0x210
> > >    [  304.345232][ T7488]       vfs_truncate+0x55c/0x66c
> > >    [  304.345252][ T7488]       __arm64_sys_truncate+0x16c/0x1e4
> > >    [  304.345272][ T7488]       invoke_syscall+0x88/0x2e0
> > >    [  304.345291][ T7488]       el0_svc_common.constprop.0+0xe8/0x2e0
> > >    [  304.345310][ T7488]       do_el0_svc+0x44/0x60
> > >    [  304.345328][ T7488]       el0_svc+0x50/0x188
> > >    [  304.345347][ T7488]       el0t_64_sync_handler+0x10c/0x140
> > >    [  304.345369][ T7488] ---------------------------------------------------
> > >    [  304.345379][ T7488] information that might be helpful
> > >    [  304.345388][ T7488] ---------------------------------------------------
> > >    [  304.345402][ T7488] CPU: 1 UID: 0 PID: 7488 Comm: syz-executor Not tainted 6.15.0-rc6-00043-ga83a69ec7f9f #5 PREEMPT
> > >    [  304.345416][ T7488] Hardware name: QEMU KVM Virtual Machine, BIOS 2025.02-8 05/13/2025
> > >    [  304.345422][ T7488] Call trace:
> > >    [  304.345426][ T7488]  show_stack+0x34/0x80 (C)
> > >    [  304.345452][ T7488]  dump_stack_lvl+0x104/0x180
> > >    [  304.345476][ T7488]  dump_stack+0x20/0x2c
> > >    [  304.345490][ T7488]  cb_check_dl+0x1080/0x10ec
> > >    [  304.345504][ T7488]  bfs+0x4d8/0x630
> > >    [  304.345514][ T7488]  add_dep+0x1cc/0x364
> > >    [  304.345526][ T7488]  __dept_wait+0x60c/0x16e0
> > >    [  304.345537][ T7488]  dept_wait+0x168/0x1a8
> > >    [  304.345548][ T7488]  btrfs_clear_buffer_dirty+0x420/0x820
> > >    [  304.345561][ T7488]  __push_leaf_right+0x8f0/0xc70
> > >    [  304.345575][ T7488]  push_leaf_right+0x408/0x628
> > >    [  304.345589][ T7488]  btrfs_del_items+0x974/0xaec
> > >    [  304.345603][ T7488]  btrfs_truncate_inode_items+0x1c5c/0x2b00
> > >    [  304.345616][ T7488]  btrfs_evict_inode+0xa4c/0xd38
> > >    [  304.345632][ T7488]  evict+0x340/0x7b0
> > >    [  304.345644][ T7488]  iput+0x4ec/0x840
> > >    [  304.345657][ T7488]  do_unlinkat+0x444/0x59c
> > >    [  304.345671][ T7488]  __arm64_sys_unlinkat+0x11c/0x260
> > >    [  304.345685][ T7488]  invoke_syscall+0x88/0x2e0
> > >    [  304.345698][ T7488]  el0_svc_common.constprop.0+0xe8/0x2e0
> > >    [  304.345713][ T7488]  do_el0_svc+0x44/0x60
> > >    [  304.345726][ T7488]  el0_svc+0x50/0x188
> > >    [  304.345741][ T7488]  el0t_64_sync_handler+0x10c/0x140
> > >    [  304.345756][ T7488]  el0t_64_sync+0x198/0x19c
> > >    [  304.345857][ T7488] ===================================================
> > >    [  304.345995][ T7488] DEPT: Circular dependency has been detected.
> > >    [  304.346006][ T7488] 6.15.0-rc6-00043-ga83a69ec7f9f #5 Not tainted
> > >    [  304.346019][ T7488] ---------------------------------------------------
> > >    [  304.346029][ T7488] summary
> > >    [  304.346038][ T7488] ---------------------------------------------------
> > >    [  304.346049][ T7488] *** DEADLOCK ***
> > >    [  304.346049][ T7488]
> > >    [  304.346058][ T7488] context A
> > >    [  304.346069][ T7488]    [S] lock(btrfs-tree-01:0)
> > >    [  304.346082][ T7488]    [W] dept_page_wait_on_bit(pg_locked_map:0)
> > >    [  304.346095][ T7488]    [E] unlock(btrfs-tree-01:0)
> > >    [  304.346108][ T7488]
> > >    [  304.346117][ T7488] context B
> > >    [  304.346126][ T7488]    [S] (unknown)(pg_locked_map:0)
> > >    [  304.346139][ T7488]    [W] lock(btrfs-tree-01:0)
> > >    [  304.346151][ T7488]    [E] dept_page_clear_bit(pg_locked_map:0)
> > >    [  304.346164][ T7488]
> > >    [  304.346173][ T7488] [S]: start of the event context
> > >    [  304.346183][ T7488] [W]: the wait blocked
> > >    [  304.346192][ T7488] [E]: the event not reachable
> > >    [  304.346201][ T7488] ---------------------------------------------------
> > >    [  304.346211][ T7488] context A's detail
> > >    [  304.346221][ T7488] ---------------------------------------------------
> > >    [  304.346231][ T7488] context A
> > >    [  304.346240][ T7488]    [S] lock(btrfs-tree-01:0)
> > >    [  304.346253][ T7488]    [W] dept_page_wait_on_bit(pg_locked_map:0)
> > >    [  304.346266][ T7488]    [E] unlock(btrfs-tree-01:0)
> > >    [  304.346278][ T7488]
> > >    [  304.346287][ T7488] [S] lock(btrfs-tree-01:0):
> > >    [  304.346299][ T7488] [<ffff8000824f41d8>] btrfs_tree_lock_nested+0x38/0x324
> > >    [  304.346321][ T7488] stacktrace:
> > >    [  304.346330][ T7488]       down_write_nested+0xe4/0x21c
> > >    [  304.346347][ T7488]       btrfs_tree_lock_nested+0x38/0x324
> > >    [  304.346363][ T7488]       btrfs_lock_root_node+0x70/0xac
> > >    [  304.346379][ T7488]       btrfs_search_slot+0x3f8/0x2dc8
> > >    [  304.346399][ T7488]       btrfs_truncate_inode_items+0x2ec/0x2b00
> > >    [  304.346417][ T7488]       btrfs_evict_inode+0xa4c/0xd38
> > >    [  304.346438][ T7488]       evict+0x340/0x7b0
> > >    [  304.346456][ T7488]       iput+0x4ec/0x840
> > >    [  304.346473][ T7488]       do_unlinkat+0x444/0x59c
> > >    [  304.346492][ T7488]       __arm64_sys_unlinkat+0x11c/0x260
> > >    [  304.346511][ T7488]       invoke_syscall+0x88/0x2e0
> > >    [  304.346530][ T7488]       el0_svc_common.constprop.0+0xe8/0x2e0
> > >    [  304.346550][ T7488]       do_el0_svc+0x44/0x60
> > >    [  304.346568][ T7488]       el0_svc+0x50/0x188
> > >    [  304.346588][ T7488]       el0t_64_sync_handler+0x10c/0x140
> > >    [  304.346608][ T7488]       el0t_64_sync+0x198/0x19c
> > >    [  304.346623][ T7488]
> > >    [  304.346632][ T7488] [W] dept_page_wait_on_bit(pg_locked_map:0):
> > >    [  304.346644][ T7488] [<ffff8000823b1d20>] __push_leaf_right+0x8f0/0xc70
> > >    [  304.346665][ T7488] stacktrace:
> > >    [  304.346674][ T7488]       __push_leaf_right+0x8f0/0xc70
> > >    [  304.346692][ T7488]       push_leaf_right+0x408/0x628
> > >    [  304.346711][ T7488]       btrfs_del_items+0x974/0xaec
> > >    [  304.346729][ T7488]       btrfs_truncate_inode_items+0x1c5c/0x2b00
> > >    [  304.346747][ T7488]       btrfs_evict_inode+0xa4c/0xd38
> > >    [  304.346767][ T7488]       evict+0x340/0x7b0
> > >    [  304.346785][ T7488]       iput+0x4ec/0x840
> > >    [  304.346802][ T7488]       do_unlinkat+0x444/0x59c
> > >    [  304.346820][ T7488]       __arm64_sys_unlinkat+0x11c/0x260
> > >    [  304.346850][ T7488]       invoke_syscall+0x88/0x2e0
> > >    [  304.346871][ T7488]       el0_svc_common.constprop.0+0xe8/0x2e0
> > >    [  304.346891][ T7488]       do_el0_svc+0x44/0x60
> > >    [  304.346909][ T7488]       el0_svc+0x50/0x188
> > >    [  304.346928][ T7488]       el0t_64_sync_handler+0x10c/0x140
> > >    [  304.346949][ T7488]       el0t_64_sync+0x198/0x19c
> > >    [  304.346963][ T7488]
> > >    [  304.346972][ T7488] [E] unlock(btrfs-tree-01:0):
> > >    [  304.346984][ T7488] (N/A)
> > >    [  304.346994][ T7488] ---------------------------------------------------
> > >    [  304.347004][ T7488] context B's detail
> > >    [  304.347013][ T7488] ---------------------------------------------------
> > >    [  304.347023][ T7488] context B
> > >    [  304.347033][ T7488]    [S] (unknown)(pg_locked_map:0)
> > >    [  304.347046][ T7488]    [W] lock(btrfs-tree-01:0)
> > >    [  304.347058][ T7488]    [E] dept_page_clear_bit(pg_locked_map:0)
> > >    [  304.347071][ T7488]
> > >    [  304.347080][ T7488] [S] (unknown)(pg_locked_map:0):
> > >    [  304.347092][ T7488] (N/A)
> > >    [  304.347101][ T7488]
> > >    [  304.347109][ T7488] [W] lock(btrfs-tree-01:0):
> > >    [  304.347121][ T7488] [<ffff8000824f3b48>] btrfs_tree_read_lock_nested+0x38/0x330
> > >    [  304.347140][ T7488] stacktrace:
> > >    [  304.347149][ T7488]       down_read_nested+0xc8/0x368
> > >    [  304.347165][ T7488]       btrfs_tree_read_lock_nested+0x38/0x330
> > >    [  304.347181][ T7488]       btrfs_read_lock_root_node+0x70/0xb4
> > >    [  304.347198][ T7488]       btrfs_search_slot+0x34c/0x2dc8
> > >    [  304.347217][ T7488]       btrfs_lookup_file_extent+0xe0/0x128
> > >    [  304.347233][ T7488]       btrfs_get_extent+0x2cc/0x1e24
> > >    [  304.347248][ T7488]       btrfs_do_readpage+0x628/0x1258
> > >    [  304.347270][ T7488]       btrfs_read_folio+0x310/0x450
> > >    [  304.347287][ T7488]       btrfs_truncate_block+0x2c0/0xb24
> > >    [  304.347302][ T7488]       btrfs_cont_expand+0x11c/0xba8
> > >    [  304.347317][ T7488]       btrfs_setattr+0x8d8/0x10f4
> > >    [  304.347332][ T7488]       notify_change+0x900/0xfbc
> > >    [  304.347352][ T7488]       do_truncate+0x154/0x210
> > >    [  304.347374][ T7488]       vfs_truncate+0x55c/0x66c
> > >    [  304.347394][ T7488]       __arm64_sys_truncate+0x16c/0x1e4
> > >    [  304.347414][ T7488]       invoke_syscall+0x88/0x2e0
> > >    [  304.347433][ T7488]
> > >    [  304.347441][ T7488] [E] dept_page_clear_bit(pg_locked_map:0):
> > >    [  304.347453][ T7488] [<ffff80008249c284>] end_folio_read+0x3e4/0x590
> > >    [  304.347471][ T7488] stacktrace:
> > >    [  304.347480][ T7488]       folio_unlock+0x8c/0x160
> > >    [  304.347504][ T7488]       end_folio_read+0x3e4/0x590
> > >    [  304.347520][ T7488]       btrfs_do_readpage+0x830/0x1258
> > >    [  304.347536][ T7488]       btrfs_read_folio+0x310/0x450
> > >    [  304.347553][ T7488]       btrfs_truncate_block+0x2c0/0xb24
> > >    [  304.347568][ T7488]       btrfs_cont_expand+0x11c/0xba8
> > >    [  304.347583][ T7488]       btrfs_setattr+0x8d8/0x10f4
> > >    [  304.347598][ T7488]       notify_change+0x900/0xfbc
> > >    [  304.347617][ T7488]       do_truncate+0x154/0x210
> > >    [  304.347636][ T7488]       vfs_truncate+0x55c/0x66c
> > >    [  304.347656][ T7488]       __arm64_sys_truncate+0x16c/0x1e4
> > >    [  304.347676][ T7488]       invoke_syscall+0x88/0x2e0
> > >    [  304.347695][ T7488]       el0_svc_common.constprop.0+0xe8/0x2e0
> > >    [  304.347714][ T7488]       do_el0_svc+0x44/0x60
> > >    [  304.347732][ T7488]       el0_svc+0x50/0x188
> > >    [  304.347751][ T7488]       el0t_64_sync_handler+0x10c/0x140
> > >    [  304.347772][ T7488] ---------------------------------------------------
> > >    [  304.347782][ T7488] information that might be helpful
> > >    [  304.347791][ T7488] ---------------------------------------------------
> > >    [  304.347803][ T7488] CPU: 1 UID: 0 PID: 7488 Comm: syz-executor Not tainted 6.15.0-rc6-00043-ga83a69ec7f9f #5 PREEMPT
> > >    [  304.347815][ T7488] Hardware name: QEMU KVM Virtual Machine, BIOS 2025.02-8 05/13/2025
> > >    [  304.347821][ T7488] Call trace:
> > >    [  304.347825][ T7488]  show_stack+0x34/0x80 (C)
> > >    [  304.347852][ T7488]  dump_stack_lvl+0x104/0x180
> > >    [  304.347870][ T7488]  dump_stack+0x20/0x2c
> > >    [  304.347884][ T7488]  cb_check_dl+0x1080/0x10ec
> > >    [  304.347897][ T7488]  bfs+0x4d8/0x630
> > >    [  304.347906][ T7488]  add_dep+0x1cc/0x364
> > >    [  304.347917][ T7488]  __dept_wait+0x60c/0x16e0
> > >    [  304.347928][ T7488]  dept_wait+0x168/0x1a8
> > >    [  304.347940][ T7488]  btrfs_clear_buffer_dirty+0x420/0x820
> > >    [  304.347952][ T7488]  __push_leaf_right+0x8f0/0xc70
> > >    [  304.347967][ T7488]  push_leaf_right+0x408/0x628
> > >    [  304.347980][ T7488]  btrfs_del_items+0x974/0xaec
> > >    [  304.347994][ T7488]  btrfs_truncate_inode_items+0x1c5c/0x2b00
> > >    [  304.348007][ T7488]  btrfs_evict_inode+0xa4c/0xd38
> > >    [  304.348023][ T7488]  evict+0x340/0x7b0
> > >    [  304.348036][ T7488]  iput+0x4ec/0x840
> > >    [  304.348048][ T7488]  do_unlinkat+0x444/0x59c
> > >    [  304.348062][ T7488]  __arm64_sys_unlinkat+0x11c/0x260
> > >    [  304.348076][ T7488]  invoke_syscall+0x88/0x2e0
> > >    [  304.348090][ T7488]  el0_svc_common.constprop.0+0xe8/0x2e0
> > >    [  304.348105][ T7488]  do_el0_svc+0x44/0x60
> > >    [  304.348118][ T7488]  el0_svc+0x50/0x188
> > >    [  304.348132][ T7488]  el0t_64_sync_handler+0x10c/0x140
> > >    [  304.348148][ T7488]  el0t_64_sync+0x198/0x19c
> > >    [  304.386144][ T8054] BTRFS info (device loop0): first mount of filesystem 3a492a15-ac49-4ce6-945e-cef7a687c6c9
> > >    [  304.389687][ T8054] BTRFS info (device loop0): using crc32c (crc32c-arm64) checksum algorithm
> > >    [  304.389788][ T8054] BTRFS info (device loop0): using free-space-tree
> > >    [  304.701202][ T7488] BTRFS info (device loop3): last unmount of filesystem 3a492a15-ac49-4ce6-945e-cef7a687c6c9