mm/slub: Avoid list corruption when removing a slab from the full list

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 (actually a
list poison being detected).

So we need to mark and isolate the slab page with metadata corruption,
do not put it back in circulation.

Because the debug caches avoid all the fastpaths, reusing the frozen bit
to mark slab page with metadata corruption 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>

Fixes: 643b113 ("slub: enable tracking of full slabs")
Suggested-by: Hyeonggon Yoo <[email protected]>
Suggested-by: Vlastimil Babka <[email protected]>
Cc: <[email protected]>
Signed-off-by: yuan.gao <[email protected]>
Reviewed-by: Hyeonggon Yoo <[email protected]>
Acked-by: Christoph Lameter <[email protected]>
Signed-off-by: Vlastimil Babka <[email protected]>

mm/slab.h

@@ -73,6 +73,11 @@ struct slab {
 						struct {
 							unsigned inuse:16;
 							unsigned objects:15;
+							/*
+							 * If slab debugging is enabled then the
+							 * frozen bit can be reused to indicate
+							 * that the slab was corrupted
+							 */
 							unsigned frozen:1;
 						};
 					};

mm/slub.c

@@ -1409,6 +1409,11 @@ static int check_slab(struct kmem_cache *s, struct slab *slab)
 			slab->inuse, slab->objects);
 		return 0;
 	}
+	if (slab->frozen) {
+		slab_err(s, slab, "Slab disabled since SLUB metadata consistency check failed");
+		return 0;
+	}
+
 	/* Slab_pad_check fixes things up after itself */
 	slab_pad_check(s, slab);
 	return 1;
@@ -1589,6 +1594,7 @@ 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;
 }
@@ -2730,7 +2736,8 @@ 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);
 		return NULL;
 	}