From: Matthew Wilcox <willy@infradead.org>
To: Barry Song <baohua@kernel.org>
Cc: akpm@linux-foundation.org, linux-mm@kvack.org, david@kernel.org,
ljs@kernel.org, liam@infradead.org, vbabka@kernel.org,
rppt@kernel.org, surenb@google.com, mhocko@suse.com,
jack@suse.cz, pfalcato@suse.de, wanglian@kylinos.cn,
chentao@kylinos.cn, lianux.mm@gmail.com, kunwu.chan@gmail.com,
liyangouwen1@oppo.com, chrisl@kernel.org, kasong@tencent.com,
shikemeng@huaweicloud.com, nphamcs@gmail.com, bhe@redhat.com,
youngjun.park@lge.com, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, loongarch@lists.linux.dev,
linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org,
linux-s390@vger.kernel.org
Subject: Re: [PATCH v2 0/5] mm: reduce mmap_lock contention and improve page fault performance
Date: Fri, 1 May 2026 15:56:47 +0100 [thread overview]
Message-ID: <afS_L-5XeWIldTXA@casper.infradead.org> (raw)
In-Reply-To: <CAGsJ_4w0qcYmukHqsyRd0jomoyYkJjOt8b-Cgp53BgP-8QQghw@mail.gmail.com>
On Fri, May 01, 2026 at 06:49:58AM +0800, Barry Song wrote:
> 1. There is no deterministic latency for I/O completion. It depends on
> both the hardware and the software stack (bio/request queues and the
> block scheduler). Sometimes the latency is short; at other times it can
> be quite long. In such cases, a high-priority thread performing operations
> such as mprotect, unmap, prctl_set_vma, or madvise may be forced to wait
> for an unpredictable amount of time.
But does that actually happen? I find it hard to believe that thread A
unmaps a VMA while thread B is in the middle of taking a page fault in
that same VMA. mprotect() and madvise() are more likely to happen, but
it still seems really unlikely to me.
next prev parent reply other threads:[~2026-05-01 14:57 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-30 4:04 [PATCH v2 0/5] mm: reduce mmap_lock contention and improve page fault performance Barry Song (Xiaomi)
2026-04-30 4:04 ` [PATCH v2 1/5] mm/filemap: Retry fault by VMA lock if the lock was released for I/O Barry Song (Xiaomi)
2026-04-30 4:04 ` [PATCH v2 2/5] mm/swapin: Retry swapin " Barry Song (Xiaomi)
2026-04-30 4:04 ` [PATCH v2 3/5] mm: Move folio_lock_or_retry() and drop __folio_lock_or_retry() Barry Song (Xiaomi)
2026-04-30 4:04 ` [PATCH v2 4/5] mm: Don't retry page fault if folio is uptodate during swap-in Barry Song (Xiaomi)
2026-04-30 12:35 ` Matthew Wilcox
2026-05-01 16:11 ` Matthew Wilcox
2026-04-30 4:04 ` [PATCH v2 5/5] mm/filemap: Avoid retrying page faults on uptodate folios in filemap faults Barry Song (Xiaomi)
2026-04-30 12:37 ` [PATCH v2 0/5] mm: reduce mmap_lock contention and improve page fault performance Matthew Wilcox
2026-04-30 22:49 ` Barry Song
2026-05-01 14:56 ` Matthew Wilcox [this message]
2026-05-01 17:44 ` Barry Song
2026-05-01 17:57 ` Matthew Wilcox
2026-05-01 18:25 ` Barry Song
2026-05-01 19:39 ` Matthew Wilcox
2026-05-03 20:39 ` Barry Song
2026-05-03 13:13 ` Jan Kara
2026-05-03 19:55 ` Barry Song
2026-05-04 13:03 ` Jan Kara
2026-05-04 13:35 ` Barry Song
2026-05-04 14:15 ` Barry Song
2026-05-01 15:52 ` Lorenzo Stoakes
2026-05-01 16:06 ` Matthew Wilcox
2026-05-01 17:09 ` Lorenzo Stoakes
2026-05-01 17:59 ` Barry Song
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