Hi,
Per Eric's request, I forward this discussion to the list first.
My first answers are inside
-----Original Message-----
From: Eric Sandeen <sandeen@xxxxxxxxxx>
Sent: Tuesday, March 16, 2021 10:18 PM
To: David Mozes <david.mozes@xxxxxxx>
Subject: Re: Mail from David.Mozes regarding fs: avoid softlockups in s_inodes iterators commit
On 3/16/21 3:02 PM, David Mozes wrote:
> Hi Eric,
>
> I hope you are all well.
>
> I am writing to you since I think you are interested in this case.
>
This really should go to linux-fsdevel@xxxxxxxxxxxxxxx but feel free to cc: me
A few things you'd want to clarify first, though.
What is the testcase?
David> it can be consider as very high load read/write iscsi traffic based on SCST application.
> [122656.730235] sh (27931): drop_caches: 3
When/why are you running drop_caches in the first place?
David > Not sure yet, Will check.
> 5.4.8 vanilla kernel it custom
Is it vanilla, or is it custom? 5.4.8 or 5.4.80?
David> 5.4.80 small custom as I mantion.
> While looking at the code, I suspected on thecond_resched(); in
> /fs/drop_caches.c file. that you moved on commit
> 04646aebd30b99f2cfa0182435a2ec252fcb16d0
>
> I comment out the cond_resched(), and everything is running just fine for ten days.
I moved it; that shouldn't matter. You removed it - that will change behavior.
What happens if you just move it back? i.e. my patch did:
diff --git a/fs/drop_caches.c b/fs/drop_caches.c index d31b6c72b476..dc1a1d5d825b 100644
--- a/fs/drop_caches.c
+++ b/fs/drop_caches.c
@@ -35,11 +35,11 @@ static void drop_pagecache_sb(struct super_block *sb, void *unused)
spin_unlock(&inode->i_lock);
spin_unlock(&sb->s_inode_list_lock);
- cond_resched();
invalidate_mapping_pages(inode->i_mapping, 0, -1);
iput(toput_inode);
toput_inode = inode;
+ cond_resched();
spin_lock(&sb->s_inode_list_lock);
}
spin_unlock(&sb->s_inode_list_lock);
What happens if you don't delete the cond_resched, but move it back up above invalidate_mapping_pages?
David> Will test and update
Thx
David
-Eric
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ATT52578.config
Description: ATT52578.config
