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Tue, 07 Feb 2023 17:47:01 -0800 (PST) Received: from localhost ([2400:8902::f03c:93ff:fe27:642a]) by smtp.gmail.com with ESMTPSA id q12-20020a17090a2dcc00b00230a50e6eadsm198397pjm.24.2023.02.07.17.46.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 07 Feb 2023 17:46:58 -0800 (PST) Date: Wed, 8 Feb 2023 01:46:46 +0000 From: Hyeonggon Yoo <42.hyeyoo@gmail.com> To: Suren Baghdasaryan Cc: akpm@linux-foundation.org, michel@lespinasse.org, jglisse@google.com, mhocko@suse.com, vbabka@suse.cz, hannes@cmpxchg.org, mgorman@techsingularity.net, dave@stgolabs.net, willy@infradead.org, liam.howlett@oracle.com, peterz@infradead.org, ldufour@linux.ibm.com, paulmck@kernel.org, mingo@redhat.com, will@kernel.org, luto@kernel.org, songliubraving@fb.com, peterx@redhat.com, david@redhat.com, dhowells@redhat.com, hughd@google.com, bigeasy@linutronix.de, kent.overstreet@linux.dev, punit.agrawal@bytedance.com, lstoakes@gmail.com, peterjung1337@gmail.com, rientjes@google.com, axelrasmussen@google.com, joelaf@google.com, minchan@google.com, rppt@kernel.org, jannh@google.com, shakeelb@google.com, tatashin@google.com, edumazet@google.com, gthelen@google.com, gurua@google.com, arjunroy@google.com, soheil@google.com, leewalsh@google.com, posk@google.com, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, x86@kernel.org, linux-kernel@vger.kernel.org, kernel-team@android.com Subject: Re: [PATCH 1/1] mm: introduce vm_flags_reset_once to replace WRITE_ONCE vm_flags updates Message-ID: References: <20230201000116.1333160-1-surenb@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230201000116.1333160-1-surenb@google.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jan 31, 2023 at 04:01:16PM -0800, Suren Baghdasaryan wrote: > Provide vm_flags_reset_once() and replace the vm_flags updates which used > WRITE_ONCE() to prevent compiler optimizations. > > Fixes: 0cce31a0aa0e ("mm: replace vma->vm_flags direct modifications with modifier calls") > Reported-by: Hyeonggon Yoo <42.hyeyoo@gmail.com> > Signed-off-by: Suren Baghdasaryan > --- > Notes: > - The patch applies cleanly over mm-unstable > - The SHA in Fixes: line is from mm-unstable, so is... unstable > > include/linux/mm.h | 7 +++++++ > mm/mlock.c | 4 ++-- > 2 files changed, 9 insertions(+), 2 deletions(-) > > diff --git a/include/linux/mm.h b/include/linux/mm.h > index 5bf0ad48faaa..23ce04f6e91e 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -648,6 +648,13 @@ static inline void vm_flags_reset(struct vm_area_struct *vma, > vm_flags_init(vma, flags); > } > > +static inline void vm_flags_reset_once(struct vm_area_struct *vma, > + vm_flags_t flags) > +{ > + mmap_assert_write_locked(vma->vm_mm); > + WRITE_ONCE(ACCESS_PRIVATE(vma, __vm_flags), flags); > +} > + > static inline void vm_flags_set(struct vm_area_struct *vma, > vm_flags_t flags) > { > diff --git a/mm/mlock.c b/mm/mlock.c > index ed49459e343e..617469fce96d 100644 > --- a/mm/mlock.c > +++ b/mm/mlock.c > @@ -380,7 +380,7 @@ static void mlock_vma_pages_range(struct vm_area_struct *vma, > */ > if (newflags & VM_LOCKED) > newflags |= VM_IO; > - vm_flags_reset(vma, newflags); > + vm_flags_reset_once(vma, newflags); > > lru_add_drain(); > walk_page_range(vma->vm_mm, start, end, &mlock_walk_ops, NULL); > @@ -388,7 +388,7 @@ static void mlock_vma_pages_range(struct vm_area_struct *vma, > > if (newflags & VM_IO) { > newflags &= ~VM_IO; > - vm_flags_reset(vma, newflags); > + vm_flags_reset_once(vma, newflags); > } > } Reviewed-by: Hyeonggon Yoo <42.hyeyoo@gmail.com> > > -- > 2.39.1.456.gfc5497dd1b-goog >