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From: Andreas Gruenbacher <agruenba@redhat.com>
To: Baoquan He <bhe@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	gfs2@lists.linux.dev, linux-mm@kvack.org,  david@redhat.com,
	osalvador@suse.de, yanjun.zhu@linux.dev,
	 linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4 1/4] mm/gup: fix wrongly calculated returned value in fault_in_safe_writeable()
Date: Fri, 11 Apr 2025 17:07:32 +0200	[thread overview]
Message-ID: <CAHc6FU7B5ORy-97OegzZ939MjuZWdBicLjRxj_bYmG3Hm1mKSA@mail.gmail.com> (raw)
In-Reply-To: <Z/ipfCofBe99Ie+7@MiWiFi-R3L-srv>

On Fri, Apr 11, 2025 at 7:32 AM Baoquan He <bhe@redhat.com> wrote:
> On 04/10/25 at 08:43pm, Andrew Morton wrote:
> > On Thu, 10 Apr 2025 11:57:14 +0800 Baoquan He <bhe@redhat.com> wrote:
> >
> > > Not like fault_in_readable() or fault_in_writeable(), in
> > > fault_in_safe_writeable() local variable 'start' is increased page
> > > by page to loop till the whole address range is handled. However,
> > > it mistakenly calcalates the size of handled range with 'uaddr - start'.
> >
> > What are the userspace-visible runtime effects of this change?
>
> I see it mainly affect gfs2_file_direct_read(). Not sure if GFS2 people
> can sense any exceptional behaviour caused by this code bug.

Thanks for the heads up.

In gfs2, fault_in_iov_iter_writeable() is used in
gfs2_file_direct_read() and gfs2_file_read_iter(), so this potentially
affects buffered as well as direct reads. This bug could cause those
gfs2 functions to spin in a loop.

Can this fix please be sent to Linus for inclusion into 6.15?

Thanks,
Andreas



  reply	other threads:[~2025-04-11 15:07 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-04-10  3:57 [PATCH v4 0/4] mm/gup: Minor fix, cleanup and improvements Baoquan He
2025-04-10  3:57 ` [PATCH v4 1/4] mm/gup: fix wrongly calculated returned value in fault_in_safe_writeable() Baoquan He
2025-04-10  8:31   ` Oscar Salvador
2025-04-11  3:43   ` Andrew Morton
2025-04-11  5:32     ` Baoquan He
2025-04-11 15:07       ` Andreas Gruenbacher [this message]
2025-04-11 23:22         ` Andrew Morton
2025-04-11  8:44   ` David Hildenbrand
2025-04-10  3:57 ` [PATCH v4 2/4] mm/gup: remove unneeded checking in follow_page_pte() Baoquan He
2025-04-10  3:57 ` [PATCH v4 3/4] mm/gup: remove gup_fast_pgd_leaf() and clean up the relevant codes Baoquan He
2025-04-10  3:57 ` [PATCH v4 4/4] mm/gup: clean up codes in fault_in_xxx() functions Baoquan He
2025-04-11  8:54   ` David Hildenbrand
2025-04-11 11:15     ` Baoquan He
2025-04-11 11:41       ` David Hildenbrand
2025-04-13  1:07         ` Baoquan He
2025-04-13 20:02           ` David Hildenbrand
2025-04-13  2:04   ` [PATCH v5 " Baoquan He
2025-04-13 20:09     ` David Hildenbrand
2025-04-14  3:44       ` Baoquan He

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