From: Matthew Wilcox <willy@infradead.org>
To: Brian Geffon <bgeffon@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Zi Yan <ziy@nvidia.com>, Kefeng Wang <wangkefeng.wang@huawei.com>,
Suren Baghdasaryan <surenb@google.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
stable@vger.kernel.org,
Baolin Wang <baolin.wang@linux.alibaba.com>,
Hugh Dickins <hughd@google.com>,
Marek Maslanka <mmaslanka@google.com>
Subject: Re: [PATCH] mm: fix finish_fault() handling for large folios
Date: Wed, 26 Feb 2025 14:03:59 +0000 [thread overview]
Message-ID: <Z78fT2H3BFVv50oI@casper.infradead.org> (raw)
In-Reply-To: <20250226114815.758217-1-bgeffon@google.com>
On Wed, Feb 26, 2025 at 06:48:15AM -0500, Brian Geffon wrote:
> When handling faults for anon shmem finish_fault() will attempt to install
> ptes for the entire folio. Unfortunately if it encounters a single
> non-pte_none entry in that range it will bail, even if the pte that
> triggered the fault is still pte_none. When this situation happens the
> fault will be retried endlessly never making forward progress.
>
> This patch fixes this behavior and if it detects that a pte in the range
> is not pte_none it will fall back to setting just the pte for the
> address that triggered the fault.
Surely there's a similar problem in do_anonymous_page()?
At any rate, what a horrid function finish_fault() has become.
Special cases all over the place. What we should be doing is
deciding the range of PTEs to insert, bounded by the folio, the VMA
and any non-none entries. Maybe I'll get a chance to fix this up.
next prev parent reply other threads:[~2025-02-26 14:04 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-02-26 11:48 [PATCH] mm: fix finish_fault() handling for large folios Brian Geffon
2025-02-26 14:03 ` Matthew Wilcox [this message]
2025-02-26 14:31 ` Brian Geffon
2025-02-26 15:42 ` David Hildenbrand
2025-02-26 16:28 ` Matthew Wilcox
2025-02-26 16:52 ` David Hildenbrand
2025-02-26 15:17 ` Baolin Wang
2025-02-26 15:46 ` Brian Geffon
2025-02-26 16:23 ` [PATCH v2] " Brian Geffon
2025-02-27 7:34 ` Baolin Wang
2025-02-27 16:47 ` Brian Geffon
2025-02-27 13:32 ` [PATCH v3] " Brian Geffon
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