From: "Huang, Ying" <ying.huang@intel.com>
To: Matthew Wilcox <willy@infradead.org>
Cc: Hugh Dickins <hughd@google.com>,
Andrew Morton <akpm@linux-foundation.org>,
Jan Kara <jack@suse.cz>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
linux-fsdevel@vger.kernel.org, Zi Yan <ziy@nvidia.com>,
Yang Shi <shy828301@gmail.com>,
Baolin Wang <baolin.wang@linux.alibaba.com>,
Oscar Salvador <osalvador@suse.de>,
Bharata B Rao <bharata@amd.com>,
Alistair Popple <apopple@nvidia.com>,
Xin Hao <xhao@linux.alibaba.com>,
Minchan Kim <minchan@kernel.org>,
Mike Kravetz <mike.kravetz@oracle.com>,
Hyeonggon Yoo <42.hyeyoo@gmail.com>,
"Xu, Pengfei" <pengfei.xu@intel.com>,
Christoph Hellwig <hch@lst.de>,
Stefan Roesch <shr@devkernel.io>, Tejun Heo <tj@kernel.org>
Subject: Re: [PATCH -v5 0/9] migrate_pages(): batch TLB flushing
Date: Tue, 21 Feb 2023 12:38:28 +0800 [thread overview]
Message-ID: <875ybveipn.fsf@yhuang6-desk2.ccr.corp.intel.com> (raw)
In-Reply-To: <Y/RI4s45PZ6Bv2ZR@casper.infradead.org> (Matthew Wilcox's message of "Tue, 21 Feb 2023 04:30:26 +0000")
Matthew Wilcox <willy@infradead.org> writes:
> On Mon, Feb 20, 2023 at 06:48:38PM -0800, Hugh Dickins wrote:
>> Yes, that's a good principle, that we should avoid to lock/wait
>> synchronously once we have locked one folio (hmm, above you say
>> "more than one": I think we mean the same thing, we're just
>> stating it differently, given how the code runs at present).
>
> I suspect the migrate page code is disobeying the locking ordering
> rules for multiple folios. if two folios belong to the same file,
> they must be locked by folio->index order, low to high. If two folios
> belong to different files, they must be ordered by folio->mapping, the
> mapping lowest in memory first. You can see this locking rule embedded
> in vfs_lock_two_folios() in fs/remap_range.c.
>
> I don't know what the locking rules are for two folios which are not file
> folios, or for two folios when one is anonymous and the other belongs
> to a file. Maybe it's the same; you can lock them ordered by ->mapping
> first, then by ->index.
>
> Or you can just trylock multiple folios and skip the ones that don't work.
Yes. We will only trylock when we have locked some folios (including
one). And retry locking only after having processed and unlocked the
already locked folios.
Best Regards,
Huang, Ying
next prev parent reply other threads:[~2023-02-21 4:39 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-13 12:34 [PATCH -v5 0/9] migrate_pages(): batch TLB flushing Huang Ying
2023-02-13 12:34 ` [PATCH -v5 1/9] migrate_pages: organize stats with struct migrate_pages_stats Huang Ying
2023-02-13 12:34 ` [PATCH -v5 2/9] migrate_pages: separate hugetlb folios migration Huang Ying
2023-02-13 12:34 ` [PATCH -v5 3/9] migrate_pages: restrict number of pages to migrate in batch Huang Ying
2023-02-13 12:34 ` [PATCH -v5 4/9] migrate_pages: split unmap_and_move() to _unmap() and _move() Huang Ying
2023-02-13 12:34 ` [PATCH -v5 5/9] migrate_pages: batch _unmap and _move Huang Ying
2023-02-13 12:34 ` [PATCH -v5 6/9] migrate_pages: move migrate_folio_unmap() Huang Ying
2023-02-13 12:34 ` [PATCH -v5 7/9] migrate_pages: share more code between _unmap and _move Huang Ying
2023-02-13 12:34 ` [PATCH -v5 8/9] migrate_pages: batch flushing TLB Huang Ying
2023-02-13 12:34 ` [PATCH -v5 9/9] migrate_pages: move THP/hugetlb migration support check to simplify code Huang Ying
2023-02-17 21:47 ` [PATCH -v5 0/9] migrate_pages(): batch TLB flushing Hugh Dickins
2023-02-20 9:28 ` Huang, Ying
2023-02-21 2:48 ` Hugh Dickins
2023-02-21 3:34 ` Huang, Ying
2023-02-21 22:15 ` Hugh Dickins
2023-02-21 4:30 ` Matthew Wilcox
2023-02-21 4:38 ` Huang, Ying [this message]
2023-02-21 14:04 ` Huang, Ying
2023-02-21 22:25 ` Hugh Dickins
2023-02-22 1:02 ` Huang, Ying
2023-02-27 11:06 ` Jan Kara
2023-02-28 1:13 ` Huang, Ying
2023-02-28 5:59 ` Hugh Dickins
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