* [PATCH] fix crash on ocfs2_duplicate_clusters_by_page
@ 2018-08-16 11:24 Larry Chen
2018-08-20 9:11 ` [Ocfs2-devel] " Gang He
0 siblings, 1 reply; 4+ messages in thread
From: Larry Chen @ 2018-08-16 11:24 UTC (permalink / raw)
To: mfasheh, jlbec; +Cc: linux-kernel, ocfs2-devel, akpm
ocfs2_duplicate_clusters_by_page may crash if an extent's page is dirty.
When a page has not been written back, it is still in dirty state. If at
that moment, ocfs2_duplicate_clusters_by_page is called against this
page, the crash happens.
To fix this bug, we can just unlock the page and wait the page until
it's not dirty.
I don't know whether the patch is appropriate, so I need comments,
thanks.
The following is the core dump:
kernel BUG at /root/code/ocfs2/refcounttree.c:2961!
__ocfs2_move_extent+0x80/0x450 [ocfs2]
? __ocfs2_claim_clusters+0x130/0x250 [ocfs2]
ocfs2_defrag_extent+0x5b8/0x5e0 [ocfs2]
__ocfs2_move_extents_range+0x2a4/0x470 [ocfs2]
ocfs2_move_extents+0x180/0x3b0 [ocfs2]
? ocfs2_wait_for_recovery+0x13/0x70 [ocfs2]
ocfs2_ioctl_move_extents+0x133/0x2d0 [ocfs2]
ocfs2_ioctl+0x253/0x640 [ocfs2]
do_vfs_ioctl+0x90/0x5f0
SyS_ioctl+0x74/0x80
do_syscall_64+0x74/0x140
entry_SYSCALL_64_after_hwframe+0x3d/0xa2
To: mfasheh@versity.com,
jlbec@evilplan.org
Cc: linux-kernel@vger.kernel.org,
ocfs2-devel@oss.oracle.com,
akpm@linux-foundation.org
Signed-off-by: Larry Chen <lchen@suse.com>
---
fs/ocfs2/refcounttree.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/fs/ocfs2/refcounttree.c b/fs/ocfs2/refcounttree.c
index 7869622af22a..ee3b9dbbc310 100644
--- a/fs/ocfs2/refcounttree.c
+++ b/fs/ocfs2/refcounttree.c
@@ -2946,6 +2946,7 @@ int ocfs2_duplicate_clusters_by_page(handle_t *handle,
if (map_end & (PAGE_SIZE - 1))
to = map_end & (PAGE_SIZE - 1);
+retry:
page = find_or_create_page(mapping, page_index, GFP_NOFS);
if (!page) {
ret = -ENOMEM;
@@ -2957,8 +2958,13 @@ int ocfs2_duplicate_clusters_by_page(handle_t *handle,
* In case PAGE_SIZE <= CLUSTER_SIZE, This page
* can't be dirtied before we CoW it out.
*/
- if (PAGE_SIZE <= OCFS2_SB(sb)->s_clustersize)
- BUG_ON(PageDirty(page));
+ if (PAGE_SIZE <= OCFS2_SB(sb)->s_clustersize) {
+ if (PageDirty(page)) {
+ unlock_page(page);
+ cond_resched();
+ goto retry;
+ }
+ }
if (!PageUptodate(page)) {
ret = block_read_full_page(page, ocfs2_get_block);
--
2.13.7
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [Ocfs2-devel] [PATCH] fix crash on ocfs2_duplicate_clusters_by_page
2018-08-16 11:24 [PATCH] fix crash on ocfs2_duplicate_clusters_by_page Larry Chen
@ 2018-08-20 9:11 ` Gang He
0 siblings, 0 replies; 4+ messages in thread
From: Gang He @ 2018-08-20 9:11 UTC (permalink / raw)
To: jlbec, Lei Chen, mfasheh; +Cc: ocfs2-devel, linux-kernel
Hello Larry,
>>> On 2018/8/16 at 19:24, in message <20180816112426.12218-1-lchen@suse.com>,
Larry Chen <lchen@suse.com> wrote:
> ocfs2_duplicate_clusters_by_page may crash if an extent's page is dirty.
> When a page has not been written back, it is still in dirty state. If at
> that moment, ocfs2_duplicate_clusters_by_page is called against this
> page, the crash happens.
>
> To fix this bug, we can just unlock the page and wait the page until
> it's not dirty.
>
> I don't know whether the patch is appropriate, so I need comments,
> thanks.
>
> The following is the core dump:
>
> kernel BUG at /root/code/ocfs2/refcounttree.c:2961!
> __ocfs2_move_extent+0x80/0x450 [ocfs2]
> ? __ocfs2_claim_clusters+0x130/0x250 [ocfs2]
> ocfs2_defrag_extent+0x5b8/0x5e0 [ocfs2]
> __ocfs2_move_extents_range+0x2a4/0x470 [ocfs2]
> ocfs2_move_extents+0x180/0x3b0 [ocfs2]
> ? ocfs2_wait_for_recovery+0x13/0x70 [ocfs2]
> ocfs2_ioctl_move_extents+0x133/0x2d0 [ocfs2]
> ocfs2_ioctl+0x253/0x640 [ocfs2]
> do_vfs_ioctl+0x90/0x5f0
> SyS_ioctl+0x74/0x80
> do_syscall_64+0x74/0x140
> entry_SYSCALL_64_after_hwframe+0x3d/0xa2
>
> To: mfasheh@versity.com,
> jlbec@evilplan.org
> Cc: linux-kernel@vger.kernel.org,
> ocfs2-devel@oss.oracle.com,
> akpm@linux-foundation.org
>
> Signed-off-by: Larry Chen <lchen@suse.com>
> ---
> fs/ocfs2/refcounttree.c | 10 ++++++++--
> 1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/fs/ocfs2/refcounttree.c b/fs/ocfs2/refcounttree.c
> index 7869622af22a..ee3b9dbbc310 100644
> --- a/fs/ocfs2/refcounttree.c
> +++ b/fs/ocfs2/refcounttree.c
> @@ -2946,6 +2946,7 @@ int ocfs2_duplicate_clusters_by_page(handle_t *handle,
> if (map_end & (PAGE_SIZE - 1))
> to = map_end & (PAGE_SIZE - 1);
>
> +retry:
> page = find_or_create_page(mapping, page_index, GFP_NOFS);
> if (!page) {
> ret = -ENOMEM;
> @@ -2957,8 +2958,13 @@ int ocfs2_duplicate_clusters_by_page(handle_t *handle,
> * In case PAGE_SIZE <= CLUSTER_SIZE, This page
> * can't be dirtied before we CoW it out.
> */
> - if (PAGE_SIZE <= OCFS2_SB(sb)->s_clustersize)
> - BUG_ON(PageDirty(page));
> + if (PAGE_SIZE <= OCFS2_SB(sb)->s_clustersize) {
> + if (PageDirty(page)) {
> + unlock_page(page);
Here, if we find this page is dirty, could we write this page to the disk initiatively? rather than wait for the page become clean by VM mechanism.
Thanks
Gang
> + cond_resched();
> + goto retry;
> + }
> + }
>
> if (!PageUptodate(page)) {
> ret = block_read_full_page(page, ocfs2_get_block);
> --
> 2.13.7
>
>
> _______________________________________________
> Ocfs2-devel mailing list
> Ocfs2-devel@oss.oracle.com
> https://oss.oracle.com/mailman/listinfo/ocfs2-devel
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [Ocfs2-devel] [PATCH] fix crash on ocfs2_duplicate_clusters_by_page
2018-08-30 2:29 ` [Ocfs2-devel] " Changwei Ge
@ 2018-08-30 2:40 ` Larry Chen
0 siblings, 0 replies; 4+ messages in thread
From: Larry Chen @ 2018-08-30 2:40 UTC (permalink / raw)
To: Changwei Ge, Andrew Morton; +Cc: ocfs2-devel, linux-kernel
Hi Andrew and Changwei,
Thanks for your review, I'll propose a new version with comments corrected.
Thanks,
Larry
On 08/30/2018 10:29 AM, Changwei Ge wrote:
> Hi Larry,
>
> Besides Andrew's comments, other parts of this patch look good to me.
>
> Thanks,
>
> Changwei
>
>
> On 2018/8/30 6:25, Andrew Morton wrote:
>> On Wed, 29 Aug 2018 15:47:40 +0800 Larry Chen <lchen@suse.com> wrote:
>>
>>> ocfs2_duplicate_clusters_by_page may crash if one of extent's pages is dirty.
>>> When a page has not been written back, it is still in dirty state. If
>>> ocfs2_duplicate_clusters_by_page is called against the
>>> dirty page, the crash happens.
>>>
>>> To fix this bug, we can just unlock the page and wait the page until
>>> it's not dirty.
>>>
>>> The following is the buck trace dump:
>>>
>>> kernel BUG at /root/code/ocfs2/refcounttree.c:2961!
>>> [exception RIP: ocfs2_duplicate_clusters_by_page+822]
>>> __ocfs2_move_extent+0x80/0x450 [ocfs2]
>>> ? __ocfs2_claim_clusters+0x130/0x250 [ocfs2]
>>> ocfs2_defrag_extent+0x5b8/0x5e0 [ocfs2]
>>> __ocfs2_move_extents_range+0x2a4/0x470 [ocfs2]
>>> ocfs2_move_extents+0x180/0x3b0 [ocfs2]
>>> ? ocfs2_wait_for_recovery+0x13/0x70 [ocfs2]
>>> ocfs2_ioctl_move_extents+0x133/0x2d0 [ocfs2]
>>> ocfs2_ioctl+0x253/0x640 [ocfs2]
>>> do_vfs_ioctl+0x90/0x5f0
>>> SyS_ioctl+0x74/0x80
>>> do_syscall_64+0x74/0x140
>>> entry_SYSCALL_64_after_hwframe+0x3d/0xa2
>>>
>>> --- a/fs/ocfs2/refcounttree.c
>>> +++ b/fs/ocfs2/refcounttree.c
>>> @@ -2946,6 +2946,7 @@ int ocfs2_duplicate_clusters_by_page(handle_t *handle,
>>> if (map_end & (PAGE_SIZE - 1))
>>> to = map_end & (PAGE_SIZE - 1);
>>>
>>> +retry:
>>> page = find_or_create_page(mapping, page_index, GFP_NOFS);
>>> if (!page) {
>>> ret = -ENOMEM;
>>> @@ -2957,8 +2958,15 @@ int ocfs2_duplicate_clusters_by_page(handle_t *handle,
>>> * In case PAGE_SIZE <= CLUSTER_SIZE, This page
>>> * can't be dirtied before we CoW it out.
>>> */
>> Looks sane, but the below change shows that the above comment is
>> untrue. Can we please update the comment as well?
>>
>>
>>> - if (PAGE_SIZE <= OCFS2_SB(sb)->s_clustersize)
>>> - BUG_ON(PageDirty(page));
>>> + if (PAGE_SIZE <= OCFS2_SB(sb)->s_clustersize) {
>>> + if (PageDirty(page)) {
>>> + /*
>>> + * write_on_page will unlock the page on return
>>> + */
>>> + ret = write_one_page(page);
>>> + goto retry;
>>> + }
>>> + }
>>>
>>> if (!PageUptodate(page)) {
>>> ret = block_read_full_page(page, ocfs2_get_block);
>>
>> _______________________________________________
>> Ocfs2-devel mailing list
>> Ocfs2-devel@oss.oracle.com
>> https://oss.oracle.com/mailman/listinfo/ocfs2-devel
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [Ocfs2-devel] [PATCH] fix crash on ocfs2_duplicate_clusters_by_page
2018-08-29 22:25 ` Andrew Morton
@ 2018-08-30 2:29 ` Changwei Ge
2018-08-30 2:40 ` Larry Chen
0 siblings, 1 reply; 4+ messages in thread
From: Changwei Ge @ 2018-08-30 2:29 UTC (permalink / raw)
To: Andrew Morton, Larry Chen; +Cc: mfasheh, ocfs2-devel, linux-kernel
Hi Larry,
Besides Andrew's comments, other parts of this patch look good to me.
Thanks,
Changwei
On 2018/8/30 6:25, Andrew Morton wrote:
> On Wed, 29 Aug 2018 15:47:40 +0800 Larry Chen <lchen@suse.com> wrote:
>
>> ocfs2_duplicate_clusters_by_page may crash if one of extent's pages is dirty.
>> When a page has not been written back, it is still in dirty state. If
>> ocfs2_duplicate_clusters_by_page is called against the
>> dirty page, the crash happens.
>>
>> To fix this bug, we can just unlock the page and wait the page until
>> it's not dirty.
>>
>> The following is the buck trace dump:
>>
>> kernel BUG at /root/code/ocfs2/refcounttree.c:2961!
>> [exception RIP: ocfs2_duplicate_clusters_by_page+822]
>> __ocfs2_move_extent+0x80/0x450 [ocfs2]
>> ? __ocfs2_claim_clusters+0x130/0x250 [ocfs2]
>> ocfs2_defrag_extent+0x5b8/0x5e0 [ocfs2]
>> __ocfs2_move_extents_range+0x2a4/0x470 [ocfs2]
>> ocfs2_move_extents+0x180/0x3b0 [ocfs2]
>> ? ocfs2_wait_for_recovery+0x13/0x70 [ocfs2]
>> ocfs2_ioctl_move_extents+0x133/0x2d0 [ocfs2]
>> ocfs2_ioctl+0x253/0x640 [ocfs2]
>> do_vfs_ioctl+0x90/0x5f0
>> SyS_ioctl+0x74/0x80
>> do_syscall_64+0x74/0x140
>> entry_SYSCALL_64_after_hwframe+0x3d/0xa2
>>
>> --- a/fs/ocfs2/refcounttree.c
>> +++ b/fs/ocfs2/refcounttree.c
>> @@ -2946,6 +2946,7 @@ int ocfs2_duplicate_clusters_by_page(handle_t *handle,
>> if (map_end & (PAGE_SIZE - 1))
>> to = map_end & (PAGE_SIZE - 1);
>>
>> +retry:
>> page = find_or_create_page(mapping, page_index, GFP_NOFS);
>> if (!page) {
>> ret = -ENOMEM;
>> @@ -2957,8 +2958,15 @@ int ocfs2_duplicate_clusters_by_page(handle_t *handle,
>> * In case PAGE_SIZE <= CLUSTER_SIZE, This page
>> * can't be dirtied before we CoW it out.
>> */
> Looks sane, but the below change shows that the above comment is
> untrue. Can we please update the comment as well?
>
>
>> - if (PAGE_SIZE <= OCFS2_SB(sb)->s_clustersize)
>> - BUG_ON(PageDirty(page));
>> + if (PAGE_SIZE <= OCFS2_SB(sb)->s_clustersize) {
>> + if (PageDirty(page)) {
>> + /*
>> + * write_on_page will unlock the page on return
>> + */
>> + ret = write_one_page(page);
>> + goto retry;
>> + }
>> + }
>>
>> if (!PageUptodate(page)) {
>> ret = block_read_full_page(page, ocfs2_get_block);
>
> _______________________________________________
> Ocfs2-devel mailing list
> Ocfs2-devel@oss.oracle.com
> https://oss.oracle.com/mailman/listinfo/ocfs2-devel
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2018-08-30 2:41 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2018-08-16 11:24 [PATCH] fix crash on ocfs2_duplicate_clusters_by_page Larry Chen
2018-08-20 9:11 ` [Ocfs2-devel] " Gang He
2018-08-29 7:47 Larry Chen
2018-08-29 22:25 ` Andrew Morton
2018-08-30 2:29 ` [Ocfs2-devel] " Changwei Ge
2018-08-30 2:40 ` Larry Chen
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