From: Matthew Wilcox <willy@infradead.org>
To: Suren Baghdasaryan <surenb@google.com>
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, 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,
chriscli@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,
michalechner92@googlemail.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 26/35] mm: fall back to mmap_lock if vma->anon_vma is not yet set
Date: Thu, 16 Feb 2023 15:44:47 +0000 [thread overview]
Message-ID: <Y+5Pb4hGmV1YtNQp@casper.infradead.org> (raw)
In-Reply-To: <20230216051750.3125598-27-surenb@google.com>
On Wed, Feb 15, 2023 at 09:17:41PM -0800, Suren Baghdasaryan wrote:
> When vma->anon_vma is not set, page fault handler will set it by either
> reusing anon_vma of an adjacent VMA if VMAs are compatible or by
> allocating a new one. find_mergeable_anon_vma() walks VMA tree to find
> a compatible adjacent VMA and that requires not only the faulting VMA
> to be stable but also the tree structure and other VMAs inside that tree.
> Therefore locking just the faulting VMA is not enough for this search.
> Fall back to taking mmap_lock when vma->anon_vma is not set. This
> situation happens only on the first page fault and should not affect
> overall performance.
I think I asked this before, but don't remember getting an aswer.
Why do we defer setting anon_vma to the first fault? Why don't we
set it up at mmap time?
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next prev parent reply other threads:[~2023-02-16 15:45 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20230216051750.3125598-1-surenb@google.com>
[not found] ` <20230216051750.3125598-22-surenb@google.com>
2023-02-16 15:34 ` [PATCH v3 21/35] mm/mmap: write-lock adjacent VMAs if they can grow into unmapped area Liam R. Howlett
[not found] ` <CAJuCfpEkujbHNxNWcWr8bmrsMhXGcpDyraOfQaPAcOH=RQPv5A@mail.gmail.com>
2023-02-17 14:50 ` Liam R. Howlett
[not found] ` <20230216051750.3125598-27-surenb@google.com>
2023-02-16 15:44 ` Matthew Wilcox [this message]
2023-02-16 19:43 ` [PATCH v3 26/35] mm: fall back to mmap_lock if vma->anon_vma is not yet set Suren Baghdasaryan
2023-02-17 2:14 ` Suren Baghdasaryan
2023-02-17 16:05 ` Matthew Wilcox
2023-02-17 16:10 ` Suren Baghdasaryan
2023-04-03 19:49 ` Matthew Wilcox
[not found] ` <20230216051750.3125598-24-surenb@google.com>
2023-02-23 20:06 ` [PATCH v3 23/35] mm/mmap: prevent pagefault handler from racing with mmu_notifier registration Liam R. Howlett
[not found] ` <20230216051750.3125598-25-surenb@google.com>
2023-02-23 20:08 ` [PATCH v3 24/35] mm: introduce vma detached flag Liam R. Howlett
[not found] ` <20230216051750.3125598-18-surenb@google.com>
2023-02-23 20:20 ` [PATCH v3 17/35] mm/mmap: write-lock VMA before shrinking or expanding it Liam R. Howlett
2023-02-23 20:28 ` Liam R. Howlett
[not found] ` <CAJuCfpE3YtSQuXJwOYWKe1z9O4GASS9pA_FTWGkdveHb3bcMXA@mail.gmail.com>
2023-02-24 1:46 ` Liam R. Howlett
[not found] ` <CAJuCfpG4JOv4aeJ6KJDi7R649vuhc0h75230ZRJgUg8spqti8w@mail.gmail.com>
2023-02-24 16:14 ` Liam R. Howlett
2023-02-24 9:21 ` [PATCH v3 00/35] Per-VMA locks freak07
2023-02-27 16:50 ` Davidlohr Bueso
2023-02-27 17:22 ` Suren Baghdasaryan
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