From: "Lorenzo Stoakes (ARM)" <ljs@kernel.org>
To: "David Hildenbrand (Arm)" <david@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Ngoc Quy <ngocquy0700@gmail.com>,
liam@infradead.org, Vlastimil Babka <vbabka@kernel.org>,
Jann Horn <jannh@google.com>, Pedro Falcato <pfalcato@suse.de>,
Muhammad Usama Anjum <usama.anjum@collabora.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
linux-fsdevel@vger.kernel.org, stable@vger.kernel.org
Subject: Re: [PATCH] fs/proc/task_mmu: pin mm_users in do_pagemap_scan()
Date: Mon, 26 Oct 2026 13:39:39 +0000 [thread overview]
Message-ID: <at9YDZXEccL0a1Pn@gremlin> (raw)
In-Reply-To: <9aa49812-1132-458e-9bf5-6dba8b476b26@kernel.org>
On Sun, Oct 25, 2026 at 11:55:59AM +0100, David Hildenbrand (Arm) wrote:
> On 10/20/26 02:46, Andrew Morton wrote:
> > All looks good and checks out for me, thanks.
> >
> > Except...
> >
> >> --- a/fs/proc/task_mmu.c
> >> +++ b/fs/proc/task_mmu.c
> >> @@ -3231,15 +3231,18 @@ static long do_pagemap_scan(struct mm_struct *mm, unsigned long uarg)
> >> size_t n_ranges_out = 0;
> >> int ret;
> >>
> >> + if (!mm || !mmget_not_zero(mm))
> >> + return -ESRCH;
> >
> > Why the new test for !mm? The current call chain guarantees this is a
> > cant-happen and the current do_pagemap_scan will cheerfully oops if
> > mm==NULL.
>
> I'd just keep it for consistency with all the other checks in this file?
Agreed.
--
Cheers, Lorenzo
next prev parent reply other threads:[~2026-10-26 13:39 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-14 9:55 Ngoc Quy
2026-10-20 0:46 ` Andrew Morton
2026-10-25 10:55 ` David Hildenbrand (Arm)
2026-10-26 13:39 ` Lorenzo Stoakes (ARM) [this message]
2026-10-25 10:56 ` David Hildenbrand (Arm)
2026-10-26 13:25 ` Pedro Falcato
2026-10-26 14:37 ` Lorenzo Stoakes (ARM)
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