Re: [f2fs-dev] [PATCH v2] f2fs: avoid cpu lockup

From: Chao Yu
Date: Mon Jul 17 2017 - 21:41:23 EST


On 2017/7/18 6:38, Jaegeuk Kim wrote:
> On 07/17, Chao Yu wrote:
>> On 2017/7/16 9:04, Jaegeuk Kim wrote:
>>> Before retrying to flush data or dentry pages, we need to release cpu in order
>>> to prevent watchdog.
>>>
>>> Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
>>
>> Reviewed-by: Chao Yu <yuchao0@xxxxxxxxxx>
>>
>>> ---
>>> Change log from v1:
>>> - timeout more specifically
>>>
>>> fs/f2fs/checkpoint.c | 10 ++++++++++
>>> 1 file changed, 10 insertions(+)
>>>
>>> diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
>>> index 56bbf592e487..5b876f6d3f6b 100644
>>> --- a/fs/f2fs/checkpoint.c
>>> +++ b/fs/f2fs/checkpoint.c
>>> @@ -879,6 +879,7 @@ int sync_dirty_inodes(struct f2fs_sb_info *sbi, enum inode_type type)
>>> struct inode *inode;
>>> struct f2fs_inode_info *fi;
>>> bool is_dir = (type == DIR_INODE);
>>> + unsigned long ino = 0;
>>>
>>> trace_f2fs_sync_dirty_inodes_enter(sbi->sb, is_dir,
>>> get_pages(sbi, is_dir ?
>>> @@ -901,8 +902,17 @@ int sync_dirty_inodes(struct f2fs_sb_info *sbi, enum inode_type type)
>>> inode = igrab(&fi->vfs_inode);
>>> spin_unlock(&sbi->inode_lock[type]);
>>> if (inode) {
>>> + unsigned long cur_ino = inode->i_ino;
>>> +
>>> filemap_fdatawrite(inode->i_mapping);
>>> iput(inode);
>>> + /* We need to give cpu to another writers. */
>>> + if (ino == cur_ino) {
>>
>> We failed to flush dirty pages of inode due to encountering -EAGAIN of writepage?
>
> Actually, I found this from a bug case in experimental patches which just skips
> it accidently. I think WB_SYNC_ALL doesn't return EAGAIN.

Alright, thanks for explanation. :)

Thanks,

>
> Thanks,
>
>>
>> Thanks,
>>
>>> + congestion_wait(BLK_RW_ASYNC, HZ/50);
>>> + cond_resched();
>>> + } else {
>>> + ino = cur_ino;
>>> + }
>>> } else {
>>> /*
>>> * We should submit bio, since it exists several
>>>
>
> .
>