From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5CF81469832; Mon, 7 Sep 2026 11:05:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788779121; cv=none; b=E/dAURwvlj5BYrIvIY6T2aXiAQLwvbeBWvQhvNhTnX7/mkyoNN1yjq1/gxSmCs5j48fd1wg11oqEaxENTVYZhSmRxpAOaFad3nXNu83i2JHB5/GPHQzFBJLsakkLN2EelXt0ypMMHGv7Whg4uBbc1Qo2wTqrDjNe/90+Ar10obw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788779121; c=relaxed/simple; bh=gAhPEThI5K+PeUzhYbnNEzwW7sHKMRTi0p//YdseykA=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=IbS8hWF6qPNFAID/1cUDDm+nVabDTE8wBlv2WEXPGcYI9M+cu0KIPZeDSz3DGksrbVUMm+CDqPQfBQfqRACkceVWQSE2XDkRVMzLsTTRPXn6tkhF7xxg2bEpebd7hOSYP5YV/tK3Z7vNSs9e0Pc8IQ07lHdsjHibu7O89ptJyvw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=PoyOKEVN; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="PoyOKEVN" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 716671F00A3D; Mon, 7 Sep 2026 11:05:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788779120; bh=vJW6MPhOnN8P0SEk/mBUWKuIt9Xcv/RQpni+Df40/kY=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=PoyOKEVNRy4VXTHA+NBiLBYDZc6Sblto8Kaz7UsiOV0QrOkd+U6KphTUovSDNjhCz q7m+nudOTVg3uWbyUbQ1K/0rmRM9xZxyvl43eHr+m/KaV8/+Bt+iJP1qA+qLRmwqhY kfkrd57WJ4utnJF9Yh+A7rU8ghy9VxqBexyWkFemv+rw9RK9Yx+kL/BjPy8/0iVJlH fxK3oXlu/CBuDfkAR/y75njkvq7DNeDTYUABFhtRrfHzBERdZHQzIwGgUnsJnZN8fb r6NYrwXxiUhaMsRCpUBMelI1o26+9ocIx7No45lfOZwm841rcd19HgskuKzFteika5 sC5hUTUEN4gvA== Date: Mon, 7 Sep 2026 12:05:04 +0100 From: "Lorenzo Stoakes (ARM)" To: Ye Liu Cc: Miaohe Lin , Andrew Morton , Ye Liu , Michal Hocko , peterz@infradead.org, paulmck@kernel.org, mingo@redhat.com, rostedt@goodmis.org, jpoimboe@kernel.org, mic@digikod.net, oleg@redhat.com, tglx@kernel.org, david@kernel.org, nao.horiguchi@gmail.com, rafael@kernel.org, gnoack3000@gmail.com, sj@kernel.org, rientjes@google.com, shakeel.butt@linux.dev, xu.xin16@zte.com.cn, chengming.zhou@linux.dev, will@kernel.org, boqun@kernel.org, frederic@kernel.org, neeraj.upadhyay@kernel.org, joelagnelf@nvidia.com, josh@joshtriplett.org, urezki@gmail.com, juri.lelli@redhat.com, vincent.guittot@linaro.org, tony.luck@intel.com, reinette.chatre@intel.com, x86@kernel.org, paul@paul-moore.com, jmorris@namei.org, serge@hallyn.com, pavel@kernel.org, lance.yang@linux.dev, mhiramat@kernel.org, pmladek@suse.com, longman@redhat.com, mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com, qiang.zhang@linux.dev, dietmar.eggemann@arm.com, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com, kprateek.nayak@amd.com, mark.rutland@arm.com, Dave.Martin@arm.com, james.morse@arm.com, babu.moger@amd.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, rcu@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-security-module@vger.kernel.org Subject: Re: [PATCH v2 4/8] mm/memory-failure: convert process iterator to for_each_process_rculock Message-ID: References: <20260907081334.1152889-1-ye.liu@linux.dev> <20260907081334.1152889-5-ye.liu@linux.dev> Precedence: bulk X-Mailing-List: linux-security-module@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260907081334.1152889-5-ye.liu@linux.dev> On Mon, Sep 07, 2026 at 04:13:30PM +0800, Ye Liu wrote: > From: Ye Liu > > Replace the manual rcu_read_lock()/rcu_read_unlock() pairs combined > with for_each_process() loop in mm/memory-failure.c with > for_each_process_rculock(), which scopes the RCU read lock to the > loop body via scoped_guard(rcu). > > In collect_procs_file(), the page_pgoff() call now falls outside the > RCU read-side critical section. This is safe because page_pgoff() > only reads folio->index and does not traverse any RCU-protected > structures. > > Signed-off-by: Ye Liu > Acked-by: Michal Hocko > Acked-by: Miaohe Lin LGTM so: Reviewed-by: Lorenzo Stoakes (ARM) > --- > Changes in v2: > - Rename *_rcu to *_rculock > - Clarify page_pgoff() safety outside RCU lock (SJ Park) > mm/memory-failure.c | 16 ++++------------ > 1 file changed, 4 insertions(+), 12 deletions(-) > > diff --git a/mm/memory-failure.c b/mm/memory-failure.c > index a8b03e2920ba..7d93deb1f7b3 100644 > --- a/mm/memory-failure.c > +++ b/mm/memory-failure.c > @@ -555,8 +555,7 @@ static void collect_procs_anon(const struct folio *folio, > return; > > pgoff = page_pgoff(folio, page); > - rcu_read_lock(); > - for_each_process(tsk) { > + for_each_process_rculock(tsk) { > struct vm_area_struct *vma; > struct anon_vma_chain *vmac; > struct task_struct *t = task_early_kill(tsk, force_early); > @@ -572,7 +571,6 @@ static void collect_procs_anon(const struct folio *folio, > add_to_kill_anon_file(t, page, vma, to_kill, addr); > } > } > - rcu_read_unlock(); > anon_vma_unlock_read(av); > } > > @@ -589,9 +587,8 @@ static void collect_procs_file(const struct folio *folio, > pgoff_t pgoff; > > i_mmap_lock_read(mapping); > - rcu_read_lock(); > pgoff = page_pgoff(folio, page); > - for_each_process(tsk) { > + for_each_process_rculock(tsk) { > struct task_struct *t = task_early_kill(tsk, force_early); > unsigned long addr; > > @@ -611,7 +608,6 @@ static void collect_procs_file(const struct folio *folio, > add_to_kill_anon_file(t, page, vma, to_kill, addr); > } > } > - rcu_read_unlock(); > i_mmap_unlock_read(mapping); > } > > @@ -635,8 +631,7 @@ static void collect_procs_fsdax(const struct page *page, > struct task_struct *tsk; > > i_mmap_lock_read(mapping); > - rcu_read_lock(); > - for_each_process(tsk) { > + for_each_process_rculock(tsk) { > struct task_struct *t = tsk; > > /* > @@ -653,7 +648,6 @@ static void collect_procs_fsdax(const struct page *page, > add_to_kill_fsdax(t, page, vma, to_kill, pgoff); > } > } > - rcu_read_unlock(); > i_mmap_unlock_read(mapping); > } > #endif /* CONFIG_FS_DAX */ > @@ -2288,8 +2282,7 @@ static void collect_procs_pfn(struct pfn_address_space *pfn_space, > struct address_space *mapping = pfn_space->mapping; > > i_mmap_lock_read(mapping); > - rcu_read_lock(); > - for_each_process(tsk) { > + for_each_process_rculock(tsk) { > struct task_struct *t = tsk; > > t = task_early_kill(tsk, true); > @@ -2303,7 +2296,6 @@ static void collect_procs_pfn(struct pfn_address_space *pfn_space, > add_to_kill_pgoff(t, vma, to_kill, pgoff); > } > } > - rcu_read_unlock(); > i_mmap_unlock_read(mapping); > } > > -- > 2.25.1 > -- Cheers, Lorenzo