* Re: [Bug 204371] BUG kmalloc-4k (Tainted: G W ): Object padding overwritten
[not found] ` <bug-204371-206035-3TOBxXIdie@https.bugzilla.kernel.org/>
@ 2019-08-09 12:31 ` Michael Ellerman
0 siblings, 0 replies; 3+ messages in thread
From: Michael Ellerman @ 2019-08-09 12:31 UTC (permalink / raw)
To: bugzilla-daemon, linuxppc-dev, linux-btrfs
bugzilla-daemon@bugzilla.kernel.org writes:
> https://bugzilla.kernel.org/show_bug.cgi?id=204371
>
> --- Comment #10 from David Sterba (dsterba@suse.com) ---
> In my case it happened on 5.3-rc3, with a strestest. The same machine has been
> running fstests periodically, with slab debug on, but there are no slab reports
> like that.
>
> [ 8516.870046] BUG kmalloc-4k (Not tainted): Poison overwritten
> [ 8516.875873]
> -----------------------------------------------------------------------------
>
> [ 8516.885864] Disabling lock debugging due to kernel taint
> [ 8516.891312] INFO: 0x000000001c70c8c9-0x000000003cd1e164. First byte 0x16
> instead of 0x6b
> [ 8516.899717] INFO: Allocated in btrfs_read_tree_root+0x46/0x120 [btrfs]
> age=1769 cpu=7 pid=8717
> [ 8516.908544] __slab_alloc.isra.53+0x3e/0x70
> [ 8516.912861] kmem_cache_alloc_trace+0x1b0/0x330
> [ 8516.917581] btrfs_read_tree_root+0x46/0x120 [btrfs]
> [ 8516.922737] btrfs_read_fs_root+0xe/0x40 [btrfs]
> [ 8516.927552] create_reloc_root+0x17f/0x2a0 [btrfs]
> [ 8516.932536] btrfs_init_reloc_root+0x72/0xe0 [btrfs]
> [ 8516.937686] record_root_in_trans+0xbb/0xf0 [btrfs]
> [ 8516.942750] btrfs_record_root_in_trans+0x50/0x70 [btrfs]
> [ 8516.948340] start_transaction+0xa1/0x550 [btrfs]
> [ 8516.953237] __btrfs_prealloc_file_range+0xca/0x490 [btrfs]
> [ 8516.959003] btrfs_prealloc_file_range+0x10/0x20 [btrfs]
> [ 8516.964509] prealloc_file_extent_cluster+0x13e/0x2b0 [btrfs]
> [ 8516.970447] relocate_file_extent_cluster+0x8d/0x530 [btrfs]
> [ 8516.976305] relocate_data_extent+0x80/0x110 [btrfs]
> [ 8516.981469] relocate_block_group+0x473/0x720 [btrfs]
> [ 8516.986711] btrfs_relocate_block_group+0x15f/0x2c0 [btrfs]
So this is looking more like it could be a btrfs bug, given you've both
hit it using btrfs but on different platforms.
cheers
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [Bug 204371] BUG kmalloc-4k (Tainted: G W ): Object padding overwritten
[not found] ` <bug-204371-206035-O9m4mwJN9f@https.bugzilla.kernel.org/>
@ 2019-08-17 8:09 ` christophe leroy
0 siblings, 0 replies; 3+ messages in thread
From: christophe leroy @ 2019-08-17 8:09 UTC (permalink / raw)
To: bugzilla-daemon, linuxppc-dev, Andrew Morton,
Linux Memory Management List, linux-btrfs, erhard_f, Chris Mason,
Josef Bacik, David Sterba, Michael Ellerman
Le 30/07/2019 à 20:52, bugzilla-daemon@bugzilla.kernel.org a écrit :
> https://bugzilla.kernel.org/show_bug.cgi?id=204371
>
> --- Comment #2 from Andrew Morton (akpm@linux-foundation.org) ---
> (switched to email. Please respond via emailed reply-to-all, not via the
> bugzilla web interface).
Reply all replies to bugzilla-daemon@bugzilla.kernel.org only.
[...]
>
> cc'ing various people here.
Hum ... only got that email through the bugzilla interface, and CC'ed
people don't show up.
>
> I suspect proc_cgroup_show() is innocent and that perhaps
> bpf_prepare_filter() had a memory scribble. iirc there has been at
> least one recent pretty serious bpf fix applied recently. Can others
> please take a look?
>
> (Seriously - please don't modify this report via the bugzilla web interface!)
>
Haven't got the original CC'ed list, so please reply with missing Cc's
if any.
We have well progressed on this case.
Erhard made a relation being this "Object padding overwritten" issue
arising on any driver, and the presence of the BTRFS driver.
Then he was able to bisect the issue to:
commit 69d2480456d1baf027a86e530989d7bedd698d5f
Author: David Sterba <dsterba@suse.com>
Date: Fri Jun 29 10:56:44 2018 +0200
btrfs: use copy_page for copying pages instead of memcpy
Use the helper that's possibly optimized for full page copies.
Signed-off-by: David Sterba <dsterba@suse.com>
After looking in the code, it has appeared that some of the said "pages"
were allocated with "kzalloc()".
Using the patch https://patchwork.ozlabs.org/patch/1148033/ Erhard
confirmed that some btrfs functions were calling copy_page() with
misaligned destinations.
copy_page(), at least on powerpc, expects cache aligned destination.
The patch https://patchwork.ozlabs.org/patch/1148606/ fixes the issue.
Christophe
---
L'absence de virus dans ce courrier électronique a été vérifiée par le logiciel antivirus Avast.
https://www.avast.com/antivirus
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [Bug 204371] BUG kmalloc-4k (Tainted: G W ): Object padding overwritten
[not found] ` <bug-204371-206129-GvRQpDzlfW@https.bugzilla.kernel.org/>
@ 2019-08-16 14:59 ` Christophe Leroy
0 siblings, 0 replies; 3+ messages in thread
From: Christophe Leroy @ 2019-08-16 14:59 UTC (permalink / raw)
To: bugzilla-daemon; +Cc: linux-btrfs
Le 16/08/2019 à 16:38, bugzilla-daemon@bugzilla.kernel.org a écrit :
> https://bugzilla.kernel.org/show_bug.cgi?id=204371
>
> --- Comment #34 from Erhard F. (erhard_f@mailbox.org) ---
> On Fri, 16 Aug 2019 08:22:31 +0000
> bugzilla-daemon@bugzilla.kernel.org wrote:
>
>> https://bugzilla.kernel.org/show_bug.cgi?id=204371
>>
>> --- Comment #32 from Christophe Leroy (christophe.leroy@c-s.fr) ---
>> Then see if the WARNING on kfree() in btrfs_free_dummy_fs_info() is still
>> there.
> With latest changes there are no complaints of the kernel any longer. btrfs
> selftests pass, mounting and unmounting a btrfs partition works without any
> suspicious dmesg output.
>
That's good news. Will you handle submitting the patch to BTRFS file
system ?
^ permalink raw reply [flat|nested] 3+ messages in thread
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[not found] ` <bug-204371-206035-3TOBxXIdie@https.bugzilla.kernel.org/>
2019-08-09 12:31 ` [Bug 204371] BUG kmalloc-4k (Tainted: G W ): Object padding overwritten Michael Ellerman
[not found] ` <bug-204371-206035-O9m4mwJN9f@https.bugzilla.kernel.org/>
2019-08-17 8:09 ` christophe leroy
[not found] <bug-204371-206129@https.bugzilla.kernel.org/>
[not found] ` <bug-204371-206129-GvRQpDzlfW@https.bugzilla.kernel.org/>
2019-08-16 14:59 ` Christophe Leroy
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