maillist inclusion category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I8EXN6 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?... -------------------------------- 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 flags. The async path is not to care because in above scenario, it's hard to run into the async path. 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> Conflicts: mm/filemap.c Signed-off-by: Liu Shixin <liushixin2@huawei.com> --- mm/filemap.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/mm/filemap.c b/mm/filemap.c index 2eeb9978f39e..b48ec6fc8f4b 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -3168,7 +3168,14 @@ void filemap_map_pages(struct vm_fault *vmf, if (xas.xa_index >= max_idx) goto unlock; - if (mmap_miss > 0) + /* + * If there are too many pages 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 (mmap_miss > 0 && !PageWorkingset(page)) mmap_miss--; vmf->address += (xas.xa_index - last_pgoff) << PAGE_SHIFT; -- 2.25.1