The patch titled
Subject: mm/slub: fix backtrace of objects because of redzone adjustment
has been added to the -mm tree. Its filename is
mm-slub-fixing-backtrace-of-objects-because-of-redzone-adjustment.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-slub-fixing-backtrace-of-objects-because-of-redzone-adjustment.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-slub-fixing-backtrace-of-objects-because-of-redzone-adjustment.patch
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------------------------------------------------------
From: Maninder Singh <maninder1.s@xxxxxxxxxxx>
Subject: mm/slub: fix backtrace of objects because of redzone adjustment
Fix commit 8e7f37f2aaa5 ("mm: Add mem_dump_obj() to print source of memory
block")
With the current code the backtrace of an allocated object is wrong:
/ # cat /proc/meminfo
[ 14.969843] slab kmalloc-64 start c8ab0140 data offset 64 pointer offset 0 size 64 allocated at 0x6b6b6b6b
[ 14.970635] 0x6b6b6b6b
[ 14.970794] 0x6b6b6b6b
[ 14.970932] 0x6b6b6b6b
[ 14.971077] 0x6b6b6b6b
[ 14.971202] 0x6b6b6b6b
[ 14.971317] 0x6b6b6b6b
[ 14.971423] 0x6b6b6b6b
[ 14.971635] 0x6b6b6b6b
[ 14.971740] 0x6b6b6b6b
[ 14.971871] 0x6b6b6b6b
[ 14.972229] 0x6b6b6b6b
[ 14.972363] 0x6b6b6b6b
[ 14.972505] 0xa56b6b6b
[ 14.972631] 0xbbbbbbbb
[ 14.972734] 0xc8ab0400
[ 14.972891] meminfo_proc_show+0x40/0x4fc
Because the red zone was not adjusted from the object address. after
adding this fixup for redzone, the backtrace is correct:
/ # cat /proc/meminfo
[ 14.870782] slab kmalloc-64 start c8ab0140 data offset 64 pointer offset 128 size 64 allocated at meminfo_proc_show+0x40/0x4f4
[ 14.871817] meminfo_proc_show+0x40/0x4f4
[ 14.872035] seq_read_iter+0x18c/0x4c4
[ 14.872229] proc_reg_read_iter+0x84/0xac
[ 14.872433] generic_file_splice_read+0xe8/0x17c
[ 14.872621] splice_direct_to_actor+0xb8/0x290
[ 14.872747] do_splice_direct+0xa0/0xe0
[ 14.872896] do_sendfile+0x2d0/0x438
[ 14.873044] sys_sendfile64+0x12c/0x140
[ 14.873229] ret_fast_syscall+0x0/0x58
[ 14.873372] 0xbe861de4
Link: https://lkml.kernel.org/r/1615891032-29160-1-git-send-email-maninder1.s@xxxxxxxxxxx
Fixes: 8e7f37f2aaa5 ("mm: Add mem_dump_obj() to print source of memory
Signed-off-by: Vaneet Narang <v.narang@xxxxxxxxxxx>
Signed-off-by: Maninder Singh <maninder1.s@xxxxxxxxxxx>
Acked-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
Cc: Russell King <linux@xxxxxxxxxxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Cc: Pekka Enberg <penberg@xxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Dmitry Safonov <0x7f454c46@xxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/slub.c | 1 +
1 file changed, 1 insertion(+)
--- a/mm/slub.c~mm-slub-fixing-backtrace-of-objects-because-of-redzone-adjustment
+++ a/mm/slub.c
@@ -3991,6 +3991,7 @@ void kmem_obj_info(struct kmem_obj_info
!(s->flags & SLAB_STORE_USER))
return;
#ifdef CONFIG_SLUB_DEBUG
+ objp = fixup_red_left(s, objp);
trackp = get_track(s, objp, TRACK_ALLOC);
kpp->kp_ret = (void *)trackp->addr;
#ifdef CONFIG_STACKTRACE
_
Patches currently in -mm which might be from maninder1.s@xxxxxxxxxxx are
mm-slub-fixing-backtrace-of-objects-because-of-redzone-adjustment.patch
mm-slub-add-support-for-free-path-information-of-an-object.patch
arm-print-alloc-free-paths-for-address-in-registers.patch
