next inclusion category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I9OCYO CVE: NA
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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If there are too many folios that are recently evicted in a file, then they will probably continue to be evicted. In such situation, there is no positive effect to read-ahead this file since it is only a waste of IO.
The mmap_miss is increased in do_sync_mmap_readahead() and decreased in both do_async_mmap_readahead() and filemap_map_pages(). In order to skip read-ahead in above scenario, the mmap_miss have to increased exceed MMAP_LOTSAMISS. This can be done by stop decreased mmap_miss when folio has workingset flag. The async path is not to care because in above scenario, it's hard to run into the async path.
[liushixin2@huawei.com: add comments] Link: https://lkml.kernel.org/r/20240326065026.1910584-1-liushixin2@huawei.com Link: https://lkml.kernel.org/r/20240322093555.226789-3-liushixin2@huawei.com Signed-off-by: Liu Shixin liushixin2@huawei.com Reviewed-by: Jan Kara jack@suse.cz Cc: Al Viro viro@ZenIV.linux.org.uk Cc: Christian Brauner brauner@kernel.org Cc: Jinjiang Tu tujinjiang@huawei.com Cc: Matthew Wilcox (Oracle) willy@infradead.org Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Liu Shixin liushixin2@huawei.com --- mm/filemap.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-)
diff --git a/mm/filemap.c b/mm/filemap.c index 7bbe26aa9cc8..a274d2c5e232 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -3527,7 +3527,15 @@ static vm_fault_t filemap_map_folio_range(struct vm_fault *vmf, if (PageHWPoison(page + count)) goto skip;
- (*mmap_miss)++; + /* + * If there are too many folios that are recently evicted + * in a file, they will probably continue to be evicted. + * In such situation, read-ahead is only a waste of IO. + * Don't decrease mmap_miss in this scenario to make sure + * we can stop read-ahead. + */ + if (!folio_test_workingset(folio)) + (*mmap_miss)++;
/* * NOTE: If there're PTE markers, we'll leave them to be @@ -3578,7 +3586,9 @@ static vm_fault_t filemap_map_order0_folio(struct vm_fault *vmf, if (PageHWPoison(page)) return ret;
- (*mmap_miss)++; + /* See comment of filemap_map_folio_range() */ + if (!folio_test_workingset(folio)) + (*mmap_miss)++;
/* * NOTE: If there're PTE markers, we'll leave them to be