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| author | Jan Kara <jack@suse.cz> | 2024-11-26 15:52:08 +0100 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2024-12-05 19:54:44 -0800 |
| commit | a220d6b95b1ae12c7626283d7609f0a1438e6437 (patch) | |
| tree | 94f656397c6b8e6da4cd9c57add04d6ca837a037 /mm | |
| parent | 4a475c0a7eeb3368eca40fe7cb02d157eeddc77a (diff) | |
| download | lwn-a220d6b95b1ae12c7626283d7609f0a1438e6437.tar.gz lwn-a220d6b95b1ae12c7626283d7609f0a1438e6437.zip | |
Revert "readahead: properly shorten readahead when falling back to do_page_cache_ra()"
This reverts commit 7c877586da3178974a8a94577b6045a48377ff25.
Anders and Philippe have reported that recent kernels occasionally hang
when used with NFS in readahead code. The problem has been bisected to
7c877586da3 ("readahead: properly shorten readahead when falling back to
do_page_cache_ra()"). The cause of the problem is that ra->size can be
shrunk by read_pages() call and subsequently we end up calling
do_page_cache_ra() with negative (read huge positive) number of pages.
Let's revert 7c877586da3 for now until we can find a proper way how the
logic in read_pages() and page_cache_ra_order() can coexist. This can
lead to reduced readahead throughput due to readahead window confusion but
that's better than outright hangs.
Link: https://lkml.kernel.org/r/20241126145208.985-1-jack@suse.cz
Fixes: 7c877586da31 ("readahead: properly shorten readahead when falling back to do_page_cache_ra()")
Reported-by: Anders Blomdell <anders.blomdell@gmail.com>
Reported-by: Philippe Troin <phil@fifi.org>
Signed-off-by: Jan Kara <jack@suse.cz>
Tested-by: Philippe Troin <phil@fifi.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/readahead.c | 5 |
1 files changed, 2 insertions, 3 deletions
diff --git a/mm/readahead.c b/mm/readahead.c index 8f1cf599b572..ea650b8b02fb 100644 --- a/mm/readahead.c +++ b/mm/readahead.c @@ -458,8 +458,7 @@ void page_cache_ra_order(struct readahead_control *ractl, struct file_ra_state *ra, unsigned int new_order) { struct address_space *mapping = ractl->mapping; - pgoff_t start = readahead_index(ractl); - pgoff_t index = start; + pgoff_t index = readahead_index(ractl); unsigned int min_order = mapping_min_folio_order(mapping); pgoff_t limit = (i_size_read(mapping->host) - 1) >> PAGE_SHIFT; pgoff_t mark = index + ra->size - ra->async_size; @@ -522,7 +521,7 @@ void page_cache_ra_order(struct readahead_control *ractl, if (!err) return; fallback: - do_page_cache_ra(ractl, ra->size - (index - start), ra->async_size); + do_page_cache_ra(ractl, ra->size, ra->async_size); } static unsigned long ractl_max_pages(struct readahead_control *ractl, |