From: Stefan Hajnoczi <stefanha@redhat.com>
To: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: qemu-devel@nongnu.org, Max Reitz <mreitz@redhat.com>,
Kevin Wolf <kwolf@redhat.com>, Sergio Lopez <slp@redhat.com>,
qemu-block@nongnu.org
Subject: Re: [Qemu-devel] [RFC 2/2] block/file-posix: verify page cache is not used
Date: Fri, 20 Apr 2018 11:02:21 +0800 [thread overview]
Message-ID: <20180420030221.GC10319@stefanha-x1.localdomain> (raw)
In-Reply-To: <20180419090546.GA2730@work-vm>
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On Thu, Apr 19, 2018 at 10:05:47AM +0100, Dr. David Alan Gilbert wrote:
> * Stefan Hajnoczi (stefanha@redhat.com) wrote:
> > This commit is for debugging only. Do not merge it.
> >
> > mincore(2) checks whether pages are resident. Use it to verify that
> > page cache has been dropped.
> >
> > You can trigger a verification failure by mmapping the image file from
> > another process and loading a byte from a page so that it becomes
> > resident. bdrv_co_invalidate_cache() will fail while the process is
> > alive.
>
> It doesn't seem a bad diagnostic to keep in (with a switch to activate)
> for when we're faced with some weird corruption on some weird storage
> system.
Okay. It's very slow to mmap an entire image file and query mincore(2)
so it needs to be off by default.
Stefan
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next prev parent reply other threads:[~2018-04-20 3:02 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-19 7:52 [Qemu-devel] [RFC 0/2] block/file-posix: allow -drive cache.direct=off live migration Stefan Hajnoczi
2018-04-19 7:52 ` [Qemu-devel] [RFC 1/2] block/file-posix: implement bdrv_co_invalidate_cache() on Linux Stefan Hajnoczi
2018-04-19 8:13 ` Fam Zheng
2018-04-20 3:15 ` Stefan Hajnoczi
2018-04-20 3:36 ` Fam Zheng
2018-04-20 6:13 ` Kevin Wolf
2018-04-19 9:18 ` Dr. David Alan Gilbert
2018-04-20 3:21 ` Stefan Hajnoczi
2018-04-20 6:27 ` Kevin Wolf
2018-04-19 7:52 ` [Qemu-devel] [RFC 2/2] block/file-posix: verify page cache is not used Stefan Hajnoczi
2018-04-19 9:05 ` Dr. David Alan Gilbert
2018-04-20 3:02 ` Stefan Hajnoczi [this message]
2018-04-20 6:25 ` Kevin Wolf
2018-04-24 14:04 ` Stefan Hajnoczi
2018-04-24 14:29 ` Kevin Wolf
2018-04-27 10:06 ` Stefan Hajnoczi
2018-04-19 16:09 ` [Qemu-devel] [RFC 0/2] block/file-posix: allow -drive cache.direct=off live migration Eric Blake
2018-04-20 3:05 ` Stefan Hajnoczi
2018-04-20 13:53 ` Eric Blake
2018-04-24 13:43 ` Stefan Hajnoczi
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