From: Andrew Morton <akpm@linux-foundation.org>
To: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>,
linux-mm@kvack.org, stable@vger.kernel.org
Subject: Re: [PATCH 2/6] mm: Convert __do_fault() to use a folio
Date: Wed, 8 Nov 2023 13:07:51 -0800 [thread overview]
Message-ID: <20231108130751.f515f0f3c5ce5fb5b1d70fb0@linux-foundation.org> (raw)
In-Reply-To: <20231108182809.602073-3-willy@infradead.org>
On Wed, 8 Nov 2023 18:28:05 +0000 "Matthew Wilcox (Oracle)" <willy@infradead.org> wrote:
> Convert vmf->page to a folio as soon as we're going to use it. This fixes
> a bug if the fault handler returns a tail page with hardware poison;
> tail pages have an invalid page->index, so we would fail to unmap the
> page from the page tables. We actually have to unmap the entire folio (or
> mapping_evict_folio() will
Would we merely fail to unmap or is there a possibility of unmapping
some random innocent other page?
How might this bug manifest in userspace, worst case?
> fail), so use unmap_mapping_folio() instead.
>
> This also saves various calls to compound_head() hidden in lock_page(),
> put_page(), etc.
>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
> Fixes: 793917d997df ("mm/readahead: Add large folio readahead")
> Cc: stable@vger.kernel.org
As it's cc:stable I'll pluck this patch out of the rest of the series
and shall stage it for 6.7-rcX, via mm-hotfixes-unstable ->
mm-hotfixes-stable -> Linus. Unless this bug is a very minor thing?
next prev parent reply other threads:[~2023-11-08 21:08 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-08 18:28 [PATCH 0/6] Fix fault handler's handling of poisoned tail pages Matthew Wilcox (Oracle)
2023-11-08 18:28 ` [PATCH 1/6] mm: Make mapping_evict_folio() the preferred way to evict clean folios Matthew Wilcox (Oracle)
2023-11-08 18:28 ` [PATCH 2/6] mm: Convert __do_fault() to use a folio Matthew Wilcox (Oracle)
2023-11-08 21:07 ` Andrew Morton [this message]
2023-11-08 21:48 ` Matthew Wilcox
2023-11-08 18:28 ` [PATCH 3/6] mm: Use mapping_evict_folio() in truncate_error_page() Matthew Wilcox (Oracle)
2023-11-08 18:28 ` [PATCH 4/6] mm: Convert soft_offline_in_use_page() to use a folio Matthew Wilcox (Oracle)
2023-11-08 18:28 ` [PATCH 5/6] mm: Convert isolate_page() to mf_isolate_folio() Matthew Wilcox (Oracle)
2023-11-08 18:28 ` [PATCH 6/6] mm: Remove invalidate_inode_page() Matthew Wilcox (Oracle)
2023-11-08 21:10 ` [PATCH 0/6] Fix fault handler's handling of poisoned tail pages Andrew Morton
2023-11-08 21:49 ` Matthew Wilcox
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