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From: David Howells <dhowells@redhat.com>
To: Trond Myklebust <trondmy@hammerspace.com>
Cc: dhowells@redhat.com,
	"linux-cachefs@redhat.com" <linux-cachefs@redhat.com>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	"linux-nfs@vger.kernel.org" <linux-nfs@vger.kernel.org>,
	"willy@infradead.org" <willy@infradead.org>,
	"anna.schumaker@netapp.com" <anna.schumaker@netapp.com>,
	"dwysocha@redhat.com" <dwysocha@redhat.com>
Subject: Re: Can the GFP flags to releasepage() be trusted? -- was Re: [PATCH v2 3/8] nfs: Move to using the alternate fallback fscache I/O API
Date: Tue, 05 Oct 2021 14:15:40 +0100	[thread overview]
Message-ID: <1080874.1633439740@warthog.procyon.org.uk> (raw)
In-Reply-To: <23033528036059af4633f60b8325e48eab95ac36.camel@hammerspace.com>

Trond Myklebust <trondmy@hammerspace.com> wrote:

> To elaborate a bit: we used to have code here that would check whether
> the page had been cleaned but was unstable, and if an argument of
> GFP_KERNEL or above was set, we'd try to call COMMIT to ensure the page
> was synched to disk on the server (and we'd wait for that call to
> complete).
> 
> That code would end up deadlocking in all sorts of horrible ways, so we
> ended up having to pull it.

I don't think that a deadlock should be possible with this.  PG_fscache is now
only being used to indicate that a DIO write to the cache is in progress on
the page.  It will complete and remove the mark at some point.

David


  parent reply	other threads:[~2021-10-05 13:15 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-17 15:04 [RFC PATCH v2 0/8] fscache: Replace and remove old I/O API v2 David Howells
2021-09-17 15:04 ` [PATCH v2 1/8] fscache: Generalise the ->begin_read_operation method David Howells
2021-09-17 15:04 ` [PATCH v2 2/8] fscache: Implement a fallback I/O interface to replace the old API David Howells
2021-09-17 15:04 ` [PATCH v2 3/8] nfs: Move to using the alternate fallback fscache I/O API David Howells
2021-09-29 14:44   ` David Wysochanski
2021-10-01 14:42   ` David Howells
     [not found]   ` <CALF+zO=165sRYRaxPpDS7DaQCpTe-YOa4FamSoMy5FV2uuG5Yg@mail.gmail.com>
2021-10-01 14:29     ` Trond Myklebust
2021-10-01 14:51     ` Can the GFP flags to releasepage() be trusted? -- was " David Howells
2021-10-01 15:04       ` Trond Myklebust
2021-10-01 19:42         ` Matthew Wilcox
2021-10-05 13:15       ` David Howells [this message]
2021-09-17 15:04 ` [PATCH v2 4/8] 9p: (untested) Convert to using the netfs helper lib to do reads and caching David Howells
2021-09-17 15:05 ` [PATCH v2 5/8] cifs: (untested) Move to using the alternate fallback fscache I/O API David Howells
2021-09-17 15:05 ` [PATCH v2 6/8] fscache: Remove the old " David Howells
2021-09-17 15:05 ` [PATCH v2 7/8] fscache: Remove stats that are no longer used David Howells
2021-09-17 15:05 ` [PATCH v2 8/8] fscache: Update the documentation to reflect I/O API changes David Howells

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