* [f2fs-dev] [PATCH] f2fs: fix to relocate f2fs_balance_fs() in mkwrite()
@ 2019-12-06 3:31 Chao Yu
2019-12-06 4:08 ` Jaegeuk Kim
0 siblings, 1 reply; 3+ messages in thread
From: Chao Yu @ 2019-12-06 3:31 UTC (permalink / raw)
To: jaegeuk; +Cc: linux-kernel, linux-f2fs-devel
As Dinosaur Huang reported, there is a potential deadlock in between
GC and mkwrite():
Thread A Thread B
- do_page_mkwrite
- f2fs_vm_page_mkwrite
- lock_page
- f2fs_balance_fs
- mutex_lock(gc_mutex)
- f2fs_gc
- do_garbage_collect
- ra_data_block
- grab_cache_page
- f2fs_balance_fs
- mutex_lock(gc_mutex)
In order to fix this, we just move f2fs_balance_fs() out of page lock's
coverage in f2fs_vm_page_mkwrite().
Reported-by: Dinosaur Huang <dinosaur.huang@unisoc.com>
Signed-off-by: Chao Yu <yuchao0@huawei.com>
---
fs/f2fs/file.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index c0560d62dbee..ed3290225506 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -67,6 +67,8 @@ static vm_fault_t f2fs_vm_page_mkwrite(struct vm_fault *vmf)
f2fs_bug_on(sbi, f2fs_has_inline_data(inode));
+ f2fs_balance_fs(sbi, true);
+
file_update_time(vmf->vma->vm_file);
down_read(&F2FS_I(inode)->i_mmap_sem);
lock_page(page);
@@ -120,8 +122,6 @@ static vm_fault_t f2fs_vm_page_mkwrite(struct vm_fault *vmf)
out_sem:
up_read(&F2FS_I(inode)->i_mmap_sem);
- f2fs_balance_fs(sbi, dn.node_changed);
-
sb_end_pagefault(inode->i_sb);
err:
return block_page_mkwrite_return(err);
--
2.18.0.rc1
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^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [f2fs-dev] [PATCH] f2fs: fix to relocate f2fs_balance_fs() in mkwrite()
2019-12-06 3:31 [f2fs-dev] [PATCH] f2fs: fix to relocate f2fs_balance_fs() in mkwrite() Chao Yu
@ 2019-12-06 4:08 ` Jaegeuk Kim
2019-12-06 4:32 ` Chao Yu
0 siblings, 1 reply; 3+ messages in thread
From: Jaegeuk Kim @ 2019-12-06 4:08 UTC (permalink / raw)
To: Chao Yu; +Cc: linux-kernel, linux-f2fs-devel
Hi Chao,
I was testing this.
https://github.com/jaegeuk/f2fs/commit/76be33b9f1fce70dd2d3f04f66d0f78b418fe3f5
On 12/06, Chao Yu wrote:
> As Dinosaur Huang reported, there is a potential deadlock in between
> GC and mkwrite():
>
> Thread A Thread B
> - do_page_mkwrite
> - f2fs_vm_page_mkwrite
> - lock_page
> - f2fs_balance_fs
> - mutex_lock(gc_mutex)
> - f2fs_gc
> - do_garbage_collect
> - ra_data_block
> - grab_cache_page
> - f2fs_balance_fs
> - mutex_lock(gc_mutex)
>
> In order to fix this, we just move f2fs_balance_fs() out of page lock's
> coverage in f2fs_vm_page_mkwrite().
>
> Reported-by: Dinosaur Huang <dinosaur.huang@unisoc.com>
> Signed-off-by: Chao Yu <yuchao0@huawei.com>
> ---
> fs/f2fs/file.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> index c0560d62dbee..ed3290225506 100644
> --- a/fs/f2fs/file.c
> +++ b/fs/f2fs/file.c
> @@ -67,6 +67,8 @@ static vm_fault_t f2fs_vm_page_mkwrite(struct vm_fault *vmf)
>
> f2fs_bug_on(sbi, f2fs_has_inline_data(inode));
>
> + f2fs_balance_fs(sbi, true);
> +
> file_update_time(vmf->vma->vm_file);
> down_read(&F2FS_I(inode)->i_mmap_sem);
> lock_page(page);
> @@ -120,8 +122,6 @@ static vm_fault_t f2fs_vm_page_mkwrite(struct vm_fault *vmf)
> out_sem:
> up_read(&F2FS_I(inode)->i_mmap_sem);
>
> - f2fs_balance_fs(sbi, dn.node_changed);
> -
> sb_end_pagefault(inode->i_sb);
> err:
> return block_page_mkwrite_return(err);
> --
> 2.18.0.rc1
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^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [f2fs-dev] [PATCH] f2fs: fix to relocate f2fs_balance_fs() in mkwrite()
2019-12-06 4:08 ` Jaegeuk Kim
@ 2019-12-06 4:32 ` Chao Yu
0 siblings, 0 replies; 3+ messages in thread
From: Chao Yu @ 2019-12-06 4:32 UTC (permalink / raw)
To: Jaegeuk Kim; +Cc: linux-kernel, linux-f2fs-devel
Hi Jaeguek,
On 2019/12/6 12:08, Jaegeuk Kim wrote:
> Hi Chao,
>
> I was testing this.
>
> https://github.com/jaegeuk/f2fs/commit/76be33b9f1fce70dd2d3f04f66d0f78b418fe3f5
The patch looks good.
BTW, do you mind adding below call stack into your patch? I guess it
describes this ABBA deadlock with more details. :)
Thanks,
>
> On 12/06, Chao Yu wrote:
>> As Dinosaur Huang reported, there is a potential deadlock in between
>> GC and mkwrite():
>>
>> Thread A Thread B
>> - do_page_mkwrite
>> - f2fs_vm_page_mkwrite
>> - lock_page
>> - f2fs_balance_fs
>> - mutex_lock(gc_mutex)
>> - f2fs_gc
>> - do_garbage_collect
>> - ra_data_block
>> - grab_cache_page
>> - f2fs_balance_fs
>> - mutex_lock(gc_mutex)
>>
>> In order to fix this, we just move f2fs_balance_fs() out of page lock's
>> coverage in f2fs_vm_page_mkwrite().
>>
>> Reported-by: Dinosaur Huang <dinosaur.huang@unisoc.com>
>> Signed-off-by: Chao Yu <yuchao0@huawei.com>
>> ---
>> fs/f2fs/file.c | 4 ++--
>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
>> index c0560d62dbee..ed3290225506 100644
>> --- a/fs/f2fs/file.c
>> +++ b/fs/f2fs/file.c
>> @@ -67,6 +67,8 @@ static vm_fault_t f2fs_vm_page_mkwrite(struct vm_fault *vmf)
>>
>> f2fs_bug_on(sbi, f2fs_has_inline_data(inode));
>>
>> + f2fs_balance_fs(sbi, true);
>> +
>> file_update_time(vmf->vma->vm_file);
>> down_read(&F2FS_I(inode)->i_mmap_sem);
>> lock_page(page);
>> @@ -120,8 +122,6 @@ static vm_fault_t f2fs_vm_page_mkwrite(struct vm_fault *vmf)
>> out_sem:
>> up_read(&F2FS_I(inode)->i_mmap_sem);
>>
>> - f2fs_balance_fs(sbi, dn.node_changed);
>> -
>> sb_end_pagefault(inode->i_sb);
>> err:
>> return block_page_mkwrite_return(err);
>> --
>> 2.18.0.rc1
> .
>
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2019-12-06 3:31 [f2fs-dev] [PATCH] f2fs: fix to relocate f2fs_balance_fs() in mkwrite() Chao Yu
2019-12-06 4:08 ` Jaegeuk Kim
2019-12-06 4:32 ` Chao Yu
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