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From: Omar Sandoval <osandov@osandov.com>
To: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	Andrew Morton <akpm@linux-foundation.org>,
	Alexey Dobriyan <adobriyan@gmail.com>,
	Eric Biederman <ebiederm@xmission.com>,
	James Morse <james.morse@arm.com>,
	Bhupesh Sharma <bhsharma@redhat.com>,
	kernel-team@fb.com
Subject: Re: [PATCH v3 5/8] proc/kcore: hold lock during read
Date: Wed, 25 Jul 2018 16:34:11 -0700	[thread overview]
Message-ID: <20180725233411.GF16847@vader> (raw)
In-Reply-To: <7f905293-5c30-f001-987f-03caf8f36737@I-love.SAKURA.ne.jp>

On Wed, Jul 25, 2018 at 12:11:26AM +0900, Tetsuo Handa wrote:
> On 2018/07/19 7:58, Omar Sandoval wrote:
> > From: Omar Sandoval <osandov@fb.com>
> > 
> > Now that we're using an rwsem, we can hold it during the entirety of
> > read_kcore() and have a common return path. This is preparation for the
> > next change.
> > 
> > Signed-off-by: Omar Sandoval <osandov@fb.com>
> > ---
> >  fs/proc/kcore.c | 70 ++++++++++++++++++++++++++++---------------------
> >  1 file changed, 40 insertions(+), 30 deletions(-)
> > 
> > diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c
> > index 95aa988c5b5d..e317ac890871 100644
> > --- a/fs/proc/kcore.c
> > +++ b/fs/proc/kcore.c
> > @@ -440,19 +440,18 @@ static ssize_t
> >  read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos)
> >  {
> >  	char *buf = file->private_data;
> > -	ssize_t acc = 0;
> >  	size_t size, tsz;
> >  	size_t elf_buflen;
> >  	int nphdr;
> >  	unsigned long start;
> > +	size_t orig_buflen = buflen;
> > +	int ret = 0;
> >  
> >  	down_read(&kclist_lock);
> 
> (...snipped...)
> 
> > +out:
> > +	up_write(&kclist_lock);
> 
> Oops. This needs to be up_read().

Yeah, thanks, I'll fix this and rerun my tests with lockdep.

  reply	other threads:[~2018-07-26  0:48 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-07-18 22:58 [PATCH v3 0/8] /proc/kcore improvements Omar Sandoval
2018-07-18 22:58 ` [PATCH v3 1/8] proc/kcore: don't grab lock for kclist_add() Omar Sandoval
2018-07-18 22:58 ` [PATCH v3 2/8] proc/kcore: don't grab lock for memory hotplug notifier Omar Sandoval
2018-07-18 22:58 ` [PATCH v3 3/8] proc/kcore: replace kclist_lock rwlock with rwsem Omar Sandoval
2018-07-18 22:58 ` [PATCH v3 4/8] proc/kcore: fix memory hotplug vs multiple opens race Omar Sandoval
2018-07-18 22:58 ` [PATCH v3 5/8] proc/kcore: hold lock during read Omar Sandoval
2018-07-24 15:11   ` Tetsuo Handa
2018-07-25 23:34     ` Omar Sandoval [this message]
2018-07-18 22:58 ` [PATCH v3 6/8] proc/kcore: clean up ELF header generation Omar Sandoval
2018-07-18 22:58 ` [PATCH v3 7/8] proc/kcore: optimize multiple page reads Omar Sandoval
2018-08-28 10:59   ` KASAN error in " Dominique Martinet
2018-08-29  4:04     ` [PATCH] proc/kcore: fix invalid memory access in multi-page read optimization Dominique Martinet
2018-09-04 18:03       ` Omar Sandoval
2018-09-04 22:24         ` Dominique Martinet
2018-09-04 22:35       ` [PATCH v2] " Dominique Martinet
2018-09-04 22:38         ` [PATCH v3] " Dominique Martinet
2018-09-04 22:41           ` Omar Sandoval
2018-09-05 19:56             ` Bhupesh Sharma
2018-09-05 20:57           ` Andrew Morton
2018-09-05 22:00             ` Dominique Martinet
2018-07-18 22:58 ` [PATCH v3 8/8] proc/kcore: add vmcoreinfo note to /proc/kcore Omar Sandoval

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