[PATCH v3] mm/slub: Avoid list corruption when removing a slab from the full list
From: yuan.gao
Date: Fri Oct 11 2024 - 06:46:48 EST
Boot with slub_debug=UFPZ.
If allocated object failed in alloc_consistency_checks, all objects of
the slab will be marked as used, and then the slab will be removed from
the partial list.
When an object belonging to the slab got freed later, the remove_full()
function is called. Because the slab is neither on the partial list nor
on the full list, it eventually lead to a list corruption.
So we need to mark and isolate the corrupted slab page, do not put it
back in circulation.
Because the debug caches avoid all the fastpaths, reusing the frozen bit
seems to be fine.
[ 4277.385669] list_del corruption, ffffea00044b3e50->next is LIST_POISON1 (dead000000000100)
[ 4277.387023] ------------[ cut here ]------------
[ 4277.387880] kernel BUG at lib/list_debug.c:56!
[ 4277.388680] invalid opcode: 0000 [#1] PREEMPT SMP PTI
[ 4277.389562] CPU: 5 PID: 90 Comm: kworker/5:1 Kdump: loaded Tainted: G OE 6.6.1-1 #1
[ 4277.392113] Workqueue: xfs-inodegc/vda1 xfs_inodegc_worker [xfs]
[ 4277.393551] RIP: 0010:__list_del_entry_valid_or_report+0x7b/0xc0
[ 4277.394518] Code: 48 91 82 e8 37 f9 9a ff 0f 0b 48 89 fe 48 c7 c7 28 49 91 82 e8 26 f9 9a ff 0f 0b 48 89 fe 48 c7 c7 58 49 91
[ 4277.397292] RSP: 0018:ffffc90000333b38 EFLAGS: 00010082
[ 4277.398202] RAX: 000000000000004e RBX: ffffea00044b3e50 RCX: 0000000000000000
[ 4277.399340] RDX: 0000000000000002 RSI: ffffffff828f8715 RDI: 00000000ffffffff
[ 4277.400545] RBP: ffffea00044b3e40 R08: 0000000000000000 R09: ffffc900003339f0
[ 4277.401710] R10: 0000000000000003 R11: ffffffff82d44088 R12: ffff888112cf9910
[ 4277.402887] R13: 0000000000000001 R14: 0000000000000001 R15: ffff8881000424c0
[ 4277.404049] FS: 0000000000000000(0000) GS:ffff88842fd40000(0000) knlGS:0000000000000000
[ 4277.405357] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 4277.406389] CR2: 00007f2ad0b24000 CR3: 0000000102a3a006 CR4: 00000000007706e0
[ 4277.407589] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 4277.408780] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 4277.410000] PKRU: 55555554
[ 4277.410645] Call Trace:
[ 4277.411234] <TASK>
[ 4277.411777] ? die+0x32/0x80
[ 4277.412439] ? do_trap+0xd6/0x100
[ 4277.413150] ? __list_del_entry_valid_or_report+0x7b/0xc0
[ 4277.414158] ? do_error_trap+0x6a/0x90
[ 4277.414948] ? __list_del_entry_valid_or_report+0x7b/0xc0
[ 4277.415915] ? exc_invalid_op+0x4c/0x60
[ 4277.416710] ? __list_del_entry_valid_or_report+0x7b/0xc0
[ 4277.417675] ? asm_exc_invalid_op+0x16/0x20
[ 4277.418482] ? __list_del_entry_valid_or_report+0x7b/0xc0
[ 4277.419466] ? __list_del_entry_valid_or_report+0x7b/0xc0
[ 4277.420410] free_to_partial_list+0x515/0x5e0
[ 4277.421242] ? xfs_iext_remove+0x41a/0xa10 [xfs]
[ 4277.422298] xfs_iext_remove+0x41a/0xa10 [xfs]
[ 4277.423316] ? xfs_inodegc_worker+0xb4/0x1a0 [xfs]
[ 4277.424383] xfs_bmap_del_extent_delay+0x4fe/0x7d0 [xfs]
[ 4277.425490] __xfs_bunmapi+0x50d/0x840 [xfs]
[ 4277.426445] xfs_itruncate_extents_flags+0x13a/0x490 [xfs]
[ 4277.427553] xfs_inactive_truncate+0xa3/0x120 [xfs]
[ 4277.428567] xfs_inactive+0x22d/0x290 [xfs]
[ 4277.429500] xfs_inodegc_worker+0xb4/0x1a0 [xfs]
[ 4277.430479] process_one_work+0x171/0x340
[ 4277.431227] worker_thread+0x277/0x390
[ 4277.431962] ? __pfx_worker_thread+0x10/0x10
[ 4277.432752] kthread+0xf0/0x120
[ 4277.433382] ? __pfx_kthread+0x10/0x10
[ 4277.434134] ret_from_fork+0x2d/0x50
[ 4277.434837] ? __pfx_kthread+0x10/0x10
[ 4277.435566] ret_from_fork_asm+0x1b/0x30
[ 4277.436280] </TASK>
v3:
- Reuse slab->fronzen bit as a corrupted marker.
v2:
- Call remove_partial() and add_full() only for slab folios.
- https://lore.kernel.org/linux-mm/20241007091850.16959-1-yuan.gao@xxxxxxxxx/
v1:
- https://lore.kernel.org/linux-mm/20241006044755.79634-1-yuan.gao@xxxxxxxxx/
Signed-off-by: yuan.gao <yuan.gao@xxxxxxxxx>
Fixes: 643b113849d8 ("slub: enable tracking of full slabs")
Acked-by: Christoph Lameter <cl@xxxxxxxxx>
Suggested-by: Hyeonggon Yoo <42.hyeyoo@xxxxxxxxx>
Suggested-by: Vlastimil Babka <vbabka@xxxxxxx>
---
mm/slab.h | 4 ++++
mm/slub.c | 11 ++++++++++-
2 files changed, 14 insertions(+), 1 deletion(-)
diff --git a/mm/slab.h b/mm/slab.h
index 6c6fe6d630ce..7681e71d9a13 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -73,6 +73,10 @@ struct slab {
struct {
unsigned inuse:16;
unsigned objects:15;
+ /*
+ * Reuse frozen bit for slab with debug enabled:
+ * frozen == 1 means it is corrupted
+ */
unsigned frozen:1;
};
};
diff --git a/mm/slub.c b/mm/slub.c
index 5b832512044e..b9265e9f11aa 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1423,6 +1423,11 @@ static int check_slab(struct kmem_cache *s, struct slab *slab)
slab->inuse, slab->objects);
return 0;
}
+ if (slab->frozen) {
+ slab_err(s, slab, "Corrupted slab");
+ return 0;
+ }
+
/* Slab_pad_check fixes things up after itself */
slab_pad_check(s, slab);
return 1;
@@ -1603,6 +1608,7 @@ static noinline bool alloc_debug_processing(struct kmem_cache *s,
slab_fix(s, "Marking all objects used");
slab->inuse = slab->objects;
slab->freelist = NULL;
+ slab->frozen = 1; /* mark consistency-failed slab as frozen */
}
return false;
}
@@ -2744,7 +2750,10 @@ static void *alloc_single_from_partial(struct kmem_cache *s,
slab->inuse++;
if (!alloc_debug_processing(s, slab, object, orig_size)) {
- remove_partial(n, slab);
+ if (folio_test_slab(slab_folio(slab))) {
+ remove_partial(n, slab);
+ add_full(s, n, slab);
+ }
return NULL;
}
--
2.32.0