From: Jan Kara <jack@suse.cz>
To: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
Hugh Dickins <hughd@google.com>,
William Kucharski <william.kucharski@oracle.com>,
Johannes Weiner <hannes@cmpxchg.org>, Jan Kara <jack@suse.cz>,
Yang Shi <yang.shi@linux.alibaba.com>,
Dave Chinner <dchinner@redhat.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 05/12] mm: Add and use find_lock_entries
Date: Tue, 29 Sep 2020 10:58:55 +0200 [thread overview]
Message-ID: <20200929085855.GD10896@quack2.suse.cz> (raw)
In-Reply-To: <20200914130042.11442-6-willy@infradead.org>
On Mon 14-09-20 14:00:35, Matthew Wilcox (Oracle) wrote:
> We have three functions (shmem_undo_range(), truncate_inode_pages_range()
> and invalidate_mapping_pages()) which want exactly this function, so
> add it to filemap.c.
>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
> diff --git a/mm/shmem.c b/mm/shmem.c
...
> index b65263d9bb67..a73ce8ce28e3 100644
> --- a/mm/shmem.c
> +++ b/mm/shmem.c
> @@ -905,12 +905,8 @@ static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
>
> pagevec_init(&pvec);
> index = start;
> - while (index < end) {
> - pvec.nr = find_get_entries(mapping, index,
> - min(end - index, (pgoff_t)PAGEVEC_SIZE),
> - pvec.pages, indices);
> - if (!pvec.nr)
> - break;
> + while (index < end && find_lock_entries(mapping, index, end - 1,
> + &pvec, indices)) {
> for (i = 0; i < pagevec_count(&pvec); i++) {
> struct page *page = pvec.pages[i];
>
> @@ -925,18 +921,10 @@ static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
> index, page);
> continue;
> }
> + index += thp_nr_pages(page) - 1;
>
> - VM_BUG_ON_PAGE(page_to_pgoff(page) != index, page);
> -
> - if (!trylock_page(page))
> - continue;
> -
> - if ((!unfalloc || !PageUptodate(page)) &&
> - page_mapping(page) == mapping) {
> - VM_BUG_ON_PAGE(PageWriteback(page), page);
> - if (shmem_punch_compound(page, start, end))
> - truncate_inode_page(mapping, page);
> - }
> + if (!unfalloc || !PageUptodate(page))
> + truncate_inode_page(mapping, page);
Is dropping shmem_punch_compound() really safe? AFAICS it can also call
split_huge_page() which will try to split THP to be able to truncate it.
That being said there's another loop in shmem_undo_range() which will try
again so what you did might make a difference with performance but not much
else. But still it would be good to at least comment about this in the
changelog...
Honza
--
Jan Kara <jack@suse.com>
SUSE Labs, CR
next prev parent reply other threads:[~2020-09-29 8:59 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-14 13:00 [PATCH v2 00/12] Overhaul multi-page lookups for THP Matthew Wilcox (Oracle)
2020-09-14 13:00 ` [PATCH v2 01/12] mm: Make pagecache tagged lookups return only head pages Matthew Wilcox (Oracle)
2020-09-29 9:13 ` Jan Kara
2020-09-14 13:00 ` [PATCH v2 02/12] mm/shmem: Use pagevec_lookup in shmem_unlock_mapping Matthew Wilcox (Oracle)
2020-09-29 8:28 ` Jan Kara
2020-09-29 18:36 ` Matthew Wilcox
2020-09-14 13:00 ` [PATCH v2 03/12] mm/filemap: Add helper for finding pages Matthew Wilcox (Oracle)
2020-09-29 8:27 ` Jan Kara
2020-09-14 13:00 ` [PATCH v2 04/12] mm/filemap: Add mapping_seek_hole_data Matthew Wilcox (Oracle)
2020-09-29 8:46 ` Jan Kara
2020-09-29 12:42 ` Matthew Wilcox
2020-09-29 13:39 ` Matthew Wilcox
2020-09-14 13:00 ` [PATCH v2 05/12] mm: Add and use find_lock_entries Matthew Wilcox (Oracle)
2020-09-29 8:58 ` Jan Kara [this message]
2020-09-29 12:48 ` Matthew Wilcox
2020-09-30 10:40 ` Jan Kara
2020-09-14 13:00 ` [PATCH v2 06/12] mm: Add an 'end' parameter to find_get_entries Matthew Wilcox (Oracle)
2020-09-14 13:00 ` [PATCH v2 07/12] mm: Add an 'end' parameter to pagevec_lookup_entries Matthew Wilcox (Oracle)
2020-09-29 9:02 ` Jan Kara
2020-09-14 13:00 ` [PATCH v2 08/12] mm: Remove nr_entries parameter from pagevec_lookup_entries Matthew Wilcox (Oracle)
2020-09-29 9:03 ` Jan Kara
2020-09-14 13:00 ` [PATCH v2 09/12] mm: Pass pvec directly to find_get_entries Matthew Wilcox (Oracle)
2020-09-29 9:07 ` Jan Kara
2020-09-14 13:00 ` [PATCH v2 10/12] mm: Remove pagevec_lookup_entries Matthew Wilcox (Oracle)
2020-09-29 9:08 ` Jan Kara
2020-09-14 13:00 ` [PATCH v2 11/12] mm/truncate,shmem: Handle truncates that split THPs Matthew Wilcox (Oracle)
2020-09-30 11:59 ` Jan Kara
2020-09-30 14:51 ` Matthew Wilcox
2020-09-14 13:00 ` [PATCH v2 12/12] mm/filemap: Return only head pages from find_get_entries Matthew Wilcox (Oracle)
2020-09-30 12:15 ` Jan Kara
2020-09-30 12:36 ` Matthew Wilcox
2020-09-30 17:08 ` Jan Kara
2020-09-30 17:23 ` Matthew Wilcox
2020-10-01 7:17 ` Jan Kara
2020-10-25 23:19 ` Matthew Wilcox
2020-10-26 9:11 ` Jan Kara
2020-09-28 20:13 ` [PATCH v2 00/12] Overhaul multi-page lookups for THP Matthew Wilcox
2020-09-29 8:50 ` William Kucharski
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