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From: Wonhuyk Yang <vvghjk1234@gmail.com>
To: willy@infradead.org
Cc: akpm@linux-foundation.org, linux-fsdevel@vger.kernel.org,
	miklos@szeredi.hu, vvghjk1234@gmail.com
Subject: Re: [PATCH] fuse: fix panic in __readahead_batch()
Date: Wed,  4 Nov 2020 10:20:17 +0900	[thread overview]
Message-ID: <20201104012017.19311-1-vvghjk1234@gmail.com> (raw)
In-Reply-To: <20201103143828.GU27442@casper.infradead.org>

From: Wonhyuk Yang <vvghjk1234@gmail.com>

Thank you for your reply.

> By the way, this isn't right.  You meant 'if (xa_is_value(page))'.

I think you missed a ! operator. Actually I was not sure that there
are other internal entries except retry entry and zero entry in 
the xas_for_each(). 

> The reason we can see a retry entry here is that we did a readahead of a
> single page at index 0.  Between that page being inserted and the lookup,
> another page was removed from the file (maybe the file was truncated
> down) and this caused the node to be removed, and the pointer to the
> page got moved into the root of the tree.  The pointer in the node was
> replaced with a retry entry, indicating that the page is still valid,
> it just isn't here any more.  And so we retry the lookup.

It's a little difficult for me, but thank you for your specific explanation.

  reply	other threads:[~2020-11-04  1:20 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-03 12:43 [PATCH] fuse: fix panic in __readahead_batch() Wonhyuk Yang
2020-11-03 14:21 ` Matthew Wilcox
2020-11-03 14:38 ` Matthew Wilcox
2020-11-04  1:20   ` Wonhuyk Yang [this message]
2020-11-04  3:59     ` Amy Parker
2020-11-04  5:12       ` Wonhuyk Yang
2020-11-10  6:54 ` [fuse] 51ac7c8929: fio.read_iops -88.2% regression kernel test robot

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