From: Suren Baghdasaryan <surenb@google.com>
To: Mel Gorman <mgorman@techsingularity.net>
Cc: akpm@linux-foundation.org, michel@lespinasse.org,
jglisse@google.com, mhocko@suse.com, vbabka@suse.cz,
hannes@cmpxchg.org, 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,
jannh@google.com, shakeelb@google.com, tatashin@google.com,
edumazet@google.com, gthelen@google.com, gurua@google.com,
arjunroy@google.com, soheil@google.com, hughlynch@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 v3 6/7] mm: introduce mod_vm_flags_nolock and use it in untrack_pfn
Date: Thu, 26 Jan 2023 08:18:31 -0800 [thread overview]
Message-ID: <CAJuCfpHP6hQAWZr2exZEXOzLbMNU_c9qNNc7pa2NYAhYLe=EKQ@mail.gmail.com> (raw)
In-Reply-To: <20230126154740.j3a3lu4x557c56yi@techsingularity.net>
On Thu, Jan 26, 2023 at 7:47 AM Mel Gorman <mgorman@techsingularity.net> wrote:
>
> On Wed, Jan 25, 2023 at 03:35:53PM -0800, Suren Baghdasaryan wrote:
> > In cases when VMA flags are modified after VMA was isolated and mmap_lock
> > was downgraded, flags modifications would result in an assertion because
> > mmap write lock is not held.
>
> Add note that it's also used during exit when the locking of the VMAs
> becomes irrelevant (mm users is 0, should be no VMA modifications taking
> place other than zap).
Ack.
>
> The typical naming pattern when a caller either knows it holds the necessary
> lock or knows it does not matter is __mod_vm_flags()
Ok. It sounds less explicit but plenty of examples, so I'm fine with
such rename. Will apply in the next version.
>
> > Introduce mod_vm_flags_nolock to be used in such situation, when VMA is
> > not part of VMA tree and locking it is not required.
>
> Instead of such situations, describe in as "used when the caller takes
> responsibility for the required locking".
Ack.
>
> > Pass a hint to untrack_pfn to conditionally use mod_vm_flags_nolock for
> > flags modification and to avoid assertion.
> >
> > Signed-off-by: Suren Baghdasaryan <surenb@google.com>
>
> Patch itself looks ok. It strays close to being "conditional locking"
> though which might attract some complaints.
The description seems to accurately describe what's done here but I'm
open to better suggestions.
Thanks!
>
> --
> Mel Gorman
> SUSE Labs
next prev parent reply other threads:[~2023-01-26 16:19 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-25 23:35 [PATCH v3 0/7] introduce vm_flags modifier functions Suren Baghdasaryan
2023-01-25 23:35 ` [PATCH v3 1/7] kernel/fork: convert vma assignment to a memcpy Suren Baghdasaryan
2023-01-26 0:21 ` Andrew Morton
2023-01-26 0:50 ` Suren Baghdasaryan
2023-01-26 1:34 ` Andrew Morton
2023-01-26 11:52 ` Mel Gorman
2023-01-26 15:59 ` Suren Baghdasaryan
2023-01-26 17:27 ` Paul E. McKenney
2023-02-07 17:16 ` Marco Elver
2023-02-07 17:23 ` Suren Baghdasaryan
2023-02-07 17:51 ` Marco Elver
2023-01-25 23:35 ` [PATCH v3 2/7] mm: introduce vma->vm_flags wrapper functions Suren Baghdasaryan
2023-01-26 0:24 ` Andrew Morton
2023-01-26 0:51 ` Suren Baghdasaryan
2023-01-26 17:48 ` Davidlohr Bueso
2023-01-26 0:28 ` Andrew Morton
2023-01-26 0:56 ` Suren Baghdasaryan
2023-01-26 7:59 ` Michal Hocko
2023-01-26 8:33 ` Michal Hocko
2023-01-26 13:58 ` Mel Gorman
2023-01-26 16:01 ` Suren Baghdasaryan
2023-01-25 23:35 ` [PATCH v3 3/7] mm: replace VM_LOCKED_CLEAR_MASK with VM_LOCKED_MASK Suren Baghdasaryan
2023-01-26 13:59 ` Mel Gorman
2023-01-26 14:16 ` Mel Gorman
2023-01-25 23:35 ` [PATCH v3 4/7] mm: replace vma->vm_flags direct modifications with modifier calls Suren Baghdasaryan
2023-01-26 15:10 ` Mel Gorman
2023-01-26 16:10 ` Suren Baghdasaryan
2023-01-26 17:26 ` Mel Gorman
2023-01-26 17:28 ` Suren Baghdasaryan
2023-01-25 23:35 ` [PATCH v3 5/7] mm: replace vma->vm_flags indirect modification in ksm_madvise Suren Baghdasaryan
2023-01-26 15:19 ` Mel Gorman
2023-01-26 16:11 ` Suren Baghdasaryan
2023-01-25 23:35 ` [PATCH v3 6/7] mm: introduce mod_vm_flags_nolock and use it in untrack_pfn Suren Baghdasaryan
2023-01-26 8:34 ` Michal Hocko
2023-01-26 15:47 ` Mel Gorman
2023-01-26 16:18 ` Suren Baghdasaryan [this message]
2023-01-26 17:32 ` Mel Gorman
2023-01-26 17:34 ` Suren Baghdasaryan
2023-01-25 23:35 ` [PATCH v3 7/7] mm: export dump_mm() Suren Baghdasaryan
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