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* [PATCH v4] fix crash on ocfs2_duplicate_clusters_by_page
@ 2018-08-30  3:06 ` Larry Chen
  0 siblings, 0 replies; 4+ messages in thread
From: Larry Chen @ 2018-08-30  3:06 UTC (permalink / raw)
  To: mark, jlbec; +Cc: linux-kernel, ocfs2-devel, akpm

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 write back the page rather than just wait.

The following is the back trace dump:

kernel BUG at /root/code/ocfs2/refcounttree.c:2961! 
	BUG_ON(PageDirty(page));
[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


Change-log:
1. Once we find the page is dirty, we do not wait until it's clean,
   but rather we use write_one_page to write it back

2. write_one_page arguments list changed, adjust and retest this patch. 

3. Comments has been changed


Signed-off-by: Larry Chen <lchen@suse.com>
---
 fs/ocfs2/refcounttree.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/fs/ocfs2/refcounttree.c b/fs/ocfs2/refcounttree.c
index 7869622af22a..ed84d05c7d00 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;
@@ -2954,11 +2955,18 @@ 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.
+		 * In case PAGE_SIZE <= CLUSTER_SIZE, we do not expect a dirty page,
+		 * so write it back.
 		 */
-		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);
-- 
2.13.7


^ permalink raw reply related	[flat|nested] 4+ messages in thread
* [Ocfs2-devel] [PATCH v4] fix crash on ocfs2_duplicate_clusters_by_page
@ 2018-08-30  3:06 ` Larry Chen
  0 siblings, 0 replies; 4+ messages in thread
From: Larry Chen @ 2018-08-30  3:06 UTC (permalink / raw)
  To: mark, jlbec; +Cc: linux-kernel, ocfs2-devel, akpm

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 write back the page rather than just wait.

The following is the back trace dump:

kernel BUG at /root/code/ocfs2/refcounttree.c:2961! 
	BUG_ON(PageDirty(page));
[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


Change-log:
1. Once we find the page is dirty, we do not wait until it's clean,
   but rather we use write_one_page to write it back

2. write_one_page arguments list changed, adjust and retest this patch. 

3. Comments has been changed


Signed-off-by: Larry Chen <lchen@suse.com>
---
 fs/ocfs2/refcounttree.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/fs/ocfs2/refcounttree.c b/fs/ocfs2/refcounttree.c
index 7869622af22a..ed84d05c7d00 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;
@@ -2954,11 +2955,18 @@ 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.
+		 * In case PAGE_SIZE <= CLUSTER_SIZE, we do not expect a dirty page,
+		 * so write it back.
 		 */
-		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);
-- 
2.13.7

^ permalink raw reply related	[flat|nested] 4+ messages in thread
* Re: [Ocfs2-devel] [PATCH v4] fix crash on ocfs2_duplicate_clusters_by_page
  2018-08-30  3:06 ` [Ocfs2-devel] " Larry Chen
@ 2018-08-30  7:43   ` Changwei Ge
  -1 siblings, 0 replies; 4+ messages in thread
From: Changwei Ge @ 2018-08-30  7:43 UTC (permalink / raw)
  To: Larry Chen, mark, jlbec; +Cc: linux-kernel, ocfs2-devel

Hi Larry,

Did you forget to add prefix 'ocfs2: ' to your patch title line?


On 2018/8/30 11:06, Larry Chen 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 write back the page rather than just wait.
>
> The following is the back trace dump:
>
> kernel BUG at /root/code/ocfs2/refcounttree.c:2961!
> 	BUG_ON(PageDirty(page));
> [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
>
>
> Change-log:
> 1. Once we find the page is dirty, we do not wait until it's clean,
>     but rather we use write_one_page to write it back
>
> 2. write_one_page arguments list changed, adjust and retest this patch.
>
> 3. Comments has been changed
>
>
> Signed-off-by: Larry Chen <lchen@suse.com>
> ---
>   fs/ocfs2/refcounttree.c | 16 ++++++++++++----
>   1 file changed, 12 insertions(+), 4 deletions(-)
>
> diff --git a/fs/ocfs2/refcounttree.c b/fs/ocfs2/refcounttree.c
> index 7869622af22a..ed84d05c7d00 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;
> @@ -2954,11 +2955,18 @@ 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.
> +		 * In case PAGE_SIZE <= CLUSTER_SIZE, we do not expect a dirty page,
> +		 * so write it back.
>   		 */
> -		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);


^ permalink raw reply	[flat|nested] 4+ messages in thread
* [Ocfs2-devel] [PATCH v4] fix crash on ocfs2_duplicate_clusters_by_page
@ 2018-08-30  7:43   ` Changwei Ge
  0 siblings, 0 replies; 4+ messages in thread
From: Changwei Ge @ 2018-08-30  7:43 UTC (permalink / raw)
  To: Larry Chen, mark, jlbec; +Cc: linux-kernel, ocfs2-devel

Hi Larry,

Did you forget to add prefix 'ocfs2: ' to your patch title line?


On 2018/8/30 11:06, Larry Chen 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 write back the page rather than just wait.
>
> The following is the back trace dump:
>
> kernel BUG at /root/code/ocfs2/refcounttree.c:2961!
> 	BUG_ON(PageDirty(page));
> [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
>
>
> Change-log:
> 1. Once we find the page is dirty, we do not wait until it's clean,
>     but rather we use write_one_page to write it back
>
> 2. write_one_page arguments list changed, adjust and retest this patch.
>
> 3. Comments has been changed
>
>
> Signed-off-by: Larry Chen <lchen@suse.com>
> ---
>   fs/ocfs2/refcounttree.c | 16 ++++++++++++----
>   1 file changed, 12 insertions(+), 4 deletions(-)
>
> diff --git a/fs/ocfs2/refcounttree.c b/fs/ocfs2/refcounttree.c
> index 7869622af22a..ed84d05c7d00 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;
> @@ -2954,11 +2955,18 @@ 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.
> +		 * In case PAGE_SIZE <= CLUSTER_SIZE, we do not expect a dirty page,
> +		 * so write it back.
>   		 */
> -		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);

^ permalink raw reply	[flat|nested] 4+ messages in thread
end of thread, other threads:[~2018-08-30  7:43 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2018-08-30  3:06 [PATCH v4] fix crash on ocfs2_duplicate_clusters_by_page Larry Chen
2018-08-30  3:06 ` [Ocfs2-devel] " Larry Chen
2018-08-30  7:43 ` Changwei Ge
2018-08-30  7:43   ` Changwei Ge

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