From: Matthew Wilcox <willy@infradead.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Android Kernel Team <kernel-team@android.com>,
Jan Kara <jack@suse.cz>, Minchan Kim <minchan@kernel.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Linux-MM <linux-mm@kvack.org>,
Vinayak Menon <vinmenon@codeaurora.org>,
"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
Will Deacon <will@kernel.org>,
Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH 1/2] mm: Allow architectures to request 'old' entries when prefaulting
Date: Wed, 9 Dec 2020 20:32:03 +0000 [thread overview]
Message-ID: <20201209203203.GU7338@casper.infradead.org> (raw)
In-Reply-To: <CAHk-=wgVqGh402dxfhR=bx2QSH=+4kq9doarNmD77baqDKdiUg@mail.gmail.com>
On Wed, Dec 09, 2020 at 11:04:13AM -0800, Linus Torvalds wrote:
> In particular, it made it a nightmare to read what do_fault_around()
> does: it does that odd
>
> if (pmd_none(*vmf->pmd)) {
> vmf->prealloc_pte = pte_alloc_one(vmf->vma->vm_mm);
>
> and then it calls ->map_pages() (which is always filemap_map_pages(),
> except for xfs, where it is also always filemap_map_pages but it takes
> a lock first).
... which is wrong. Dave's paranoia around other people
introducing bugs into XFS made him do this, but we should revert
cd647d5651c0b0deaa26c1acb9e1789437ba9bc7. Those operations he's
worried about are protected by the page lock.
If a filesystem has put an Uptodate page into the page cache, the
rest of the kernel can read it without telling the filesystem.
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next prev parent reply other threads:[~2020-12-09 20:33 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-09 16:39 [PATCH 0/2] Create 'old' ptes for faultaround mappings on arm64 with hardware access flag Will Deacon
2020-12-09 16:39 ` [PATCH 1/2] mm: Allow architectures to request 'old' entries when prefaulting Will Deacon
2020-12-09 17:58 ` Linus Torvalds
2020-12-09 18:40 ` Will Deacon
2020-12-09 19:04 ` Linus Torvalds
2020-12-09 20:32 ` Matthew Wilcox [this message]
2020-12-09 21:04 ` Linus Torvalds
2020-12-10 15:08 ` Kirill A. Shutemov
2020-12-10 17:23 ` Linus Torvalds
2020-12-14 16:07 ` Kirill A. Shutemov
2020-12-14 17:54 ` Linus Torvalds
2020-12-14 18:56 ` Matthew Wilcox
2020-12-16 17:07 ` Kirill A. Shutemov
2020-12-16 18:41 ` Linus Torvalds
2020-12-17 10:54 ` Kirill A. Shutemov
2020-12-17 18:22 ` Linus Torvalds
2020-12-18 11:04 ` Kirill A. Shutemov
2020-12-18 18:56 ` Linus Torvalds
2020-12-19 12:41 ` Kirill A. Shutemov
2020-12-19 20:08 ` Linus Torvalds
2020-12-19 20:34 ` Linus Torvalds
2020-12-22 10:00 ` Kirill A. Shutemov
2020-12-24 4:04 ` Hugh Dickins
2020-12-25 11:31 ` Kirill A. Shutemov
2020-12-26 17:57 ` Linus Torvalds
2020-12-26 20:43 ` Kirill A. Shutemov
2020-12-26 21:03 ` Hugh Dickins
2020-12-26 21:16 ` Linus Torvalds
2020-12-26 22:40 ` Kirill A. Shutemov
2020-12-27 0:45 ` Hugh Dickins
2020-12-27 2:38 ` Hugh Dickins
2020-12-27 19:38 ` Linus Torvalds
2020-12-27 20:32 ` Damian Tometzki
2020-12-27 22:35 ` Hugh Dickins
2020-12-27 23:12 ` Linus Torvalds
2020-12-27 23:40 ` Linus Torvalds
2020-12-27 23:55 ` Kirill A. Shutemov
2020-12-27 23:48 ` Kirill A. Shutemov
2020-12-28 1:54 ` Linus Torvalds
2020-12-28 6:43 ` Hugh Dickins
2020-12-28 12:53 ` Kirill A. Shutemov
2020-12-28 18:47 ` Linus Torvalds
2020-12-28 21:58 ` Linus Torvalds
2020-12-29 13:28 ` Kirill A. Shutemov
2020-12-29 15:19 ` Matthew Wilcox
2020-12-29 20:52 ` Linus Torvalds
2020-12-28 22:05 ` Kirill A. Shutemov
2020-12-28 22:12 ` Kirill A. Shutemov
2020-12-29 4:35 ` Hugh Dickins
2020-12-28 23:28 ` Linus Torvalds
2020-12-26 21:07 ` Linus Torvalds
2020-12-26 21:41 ` Matthew Wilcox
2020-12-09 16:39 ` [PATCH 2/2] arm64: mm: Implement arch_wants_old_faultaround_pte() Will Deacon
2020-12-09 18:35 ` Catalin Marinas
2020-12-09 18:46 ` Will Deacon
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