From: Matthew Wilcox <willy@infradead.org>
To: linux-fsdevel@vger.kernel.org
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
linux-btrfs@vger.kernel.org, linux-erofs@lists.ozlabs.org,
linux-ext4@vger.kernel.org,
linux-f2fs-devel@lists.sourceforge.net, cluster-devel@redhat.com,
ocfs2-devel@oss.oracle.com, linux-xfs@vger.kernel.org,
Cong Wang <xiyou.wangcong@gmail.com>,
Michal Hocko <mhocko@suse.com>
Subject: [PATCH v6 16/16] mm: Use memalloc_nofs_save in readahead path
Date: Mon, 17 Feb 2020 10:46:10 -0800 [thread overview]
Message-ID: <20200217184613.19668-30-willy@infradead.org> (raw)
In-Reply-To: <20200217184613.19668-1-willy@infradead.org>
From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Ensure that memory allocations in the readahead path do not attempt to
reclaim file-backed pages, which could lead to a deadlock. It is
possible, though unlikely this is the root cause of a problem observed
by Cong Wang.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reported-by: Cong Wang <xiyou.wangcong@gmail.com>
Suggested-by: Michal Hocko <mhocko@suse.com>
---
mm/readahead.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/mm/readahead.c b/mm/readahead.c
index 566693f4e539..ae8abab939a3 100644
--- a/mm/readahead.c
+++ b/mm/readahead.c
@@ -22,6 +22,7 @@
#include <linux/mm_inline.h>
#include <linux/blk-cgroup.h>
#include <linux/fadvise.h>
+#include <linux/sched/mm.h>
#include "internal.h"
@@ -157,6 +158,18 @@ void page_cache_readahead_limit(struct address_space *mapping,
._nr_pages = 0,
};
+ /*
+ * Partway through the readahead operation, we will have added
+ * locked pages to the page cache, but will not yet have submitted
+ * them for I/O. Adding another page may need to allocate memory,
+ * which can trigger memory reclaim. Telling the VM we're in
+ * the middle of a filesystem operation will cause it to not
+ * touch file-backed pages, preventing a deadlock. Most (all?)
+ * filesystems already specify __GFP_NOFS in their mapping's
+ * gfp_mask, but let's be explicit here.
+ */
+ unsigned int nofs = memalloc_nofs_save();
+
/*
* Preallocate as many pages as we will need.
*/
@@ -210,6 +223,7 @@ void page_cache_readahead_limit(struct address_space *mapping,
if (readahead_count(&rac))
read_pages(&rac, &page_pool);
BUG_ON(!list_empty(&page_pool));
+ memalloc_nofs_restore(nofs);
}
EXPORT_SYMBOL_GPL(page_cache_readahead_limit);
--
2.25.0
next prev parent reply other threads:[~2020-02-17 18:49 UTC|newest]
Thread overview: 111+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-17 18:45 [PATCH v6 00/19] Change readahead API Matthew Wilcox
2020-02-17 18:45 ` [PATCH v6 01/19] mm: Return void from various readahead functions Matthew Wilcox
2020-02-18 4:47 ` Dave Chinner
2020-02-18 21:05 ` John Hubbard
2020-02-18 21:21 ` Matthew Wilcox
2020-02-18 21:52 ` John Hubbard
2020-02-17 18:45 ` [PATCH v6 02/19] mm: Ignore return value of ->readpages Matthew Wilcox
2020-02-18 4:48 ` Dave Chinner
2020-02-18 21:33 ` John Hubbard
2020-02-17 18:45 ` [PATCH v6 03/19] mm: Use readahead_control to pass arguments Matthew Wilcox
2020-02-18 5:03 ` Dave Chinner
2020-02-18 13:56 ` Matthew Wilcox
2020-02-18 22:46 ` Dave Chinner
2020-02-18 22:52 ` Matthew Wilcox
2020-02-18 22:22 ` John Hubbard
2020-02-17 18:45 ` [PATCH v6 04/19] mm: Rearrange readahead loop Matthew Wilcox
2020-02-18 5:08 ` Dave Chinner
2020-02-18 13:57 ` Matthew Wilcox
2020-02-18 22:48 ` Dave Chinner
2020-02-18 22:33 ` John Hubbard
2020-02-17 18:45 ` [PATCH v6 04/16] mm: Tweak readahead loop slightly Matthew Wilcox
2020-02-18 22:57 ` John Hubbard
2020-02-18 23:00 ` John Hubbard
2020-02-17 18:45 ` [PATCH v6 05/16] mm: Put readahead pages in cache earlier Matthew Wilcox
2020-02-17 18:45 ` [PATCH v6 05/19] mm: Remove 'page_offset' from readahead loop Matthew Wilcox
2020-02-18 5:14 ` Dave Chinner
2020-02-18 23:08 ` John Hubbard
2020-02-17 18:45 ` [PATCH v6 06/16] mm: Add readahead address space operation Matthew Wilcox
2020-02-17 18:45 ` [PATCH v6 06/19] mm: rename readahead loop variable to 'i' Matthew Wilcox
2020-02-18 5:33 ` Dave Chinner
2020-02-18 23:11 ` John Hubbard
2020-02-17 18:45 ` [PATCH v6 07/16] mm: Add page_cache_readahead_limit Matthew Wilcox
2020-02-17 18:45 ` [PATCH v6 07/19] mm: Put readahead pages in cache earlier Matthew Wilcox
2020-02-18 6:14 ` Dave Chinner
2020-02-18 15:42 ` Matthew Wilcox
2020-02-19 0:59 ` Dave Chinner
2020-02-19 0:01 ` John Hubbard
2020-02-19 1:02 ` Matthew Wilcox
2020-02-19 1:13 ` John Hubbard
2020-02-19 3:24 ` John Hubbard
2020-02-19 14:41 ` Matthew Wilcox
2020-02-19 14:52 ` Christoph Hellwig
2020-02-19 15:01 ` Matthew Wilcox
2020-02-19 20:24 ` John Hubbard
2020-02-17 18:45 ` [PATCH v6 08/16] fs: Convert mpage_readpages to mpage_readahead Matthew Wilcox
2020-02-17 18:45 ` [PATCH v6 08/19] mm: Add readahead address space operation Matthew Wilcox
2020-02-18 6:21 ` Dave Chinner
2020-02-18 16:10 ` Matthew Wilcox
2020-02-19 1:04 ` Dave Chinner
2020-02-19 0:12 ` John Hubbard
2020-02-19 3:10 ` Eric Biggers
2020-02-19 3:35 ` Eric Biggers
2020-02-19 16:52 ` Matthew Wilcox
2020-02-17 18:45 ` [PATCH v6 09/16] btrfs: Convert from readpages to readahead Matthew Wilcox
2020-02-17 18:45 ` [PATCH v6 09/19] mm: Add page_cache_readahead_limit Matthew Wilcox
2020-02-18 6:31 ` Dave Chinner
2020-02-18 19:54 ` Matthew Wilcox
2020-02-19 1:08 ` Dave Chinner
2020-02-19 1:32 ` John Hubbard
2020-02-19 2:23 ` Matthew Wilcox
2020-02-19 2:46 ` John Hubbard
2020-02-17 18:45 ` [PATCH v6 10/16] erofs: Convert uncompressed files from readpages to readahead Matthew Wilcox
2020-02-17 18:45 ` [PATCH v6 10/19] fs: Convert mpage_readpages to mpage_readahead Matthew Wilcox
2020-02-18 1:51 ` [Ocfs2-devel] " Joseph Qi
2020-02-18 6:37 ` Dave Chinner
2020-02-19 2:48 ` John Hubbard
2020-02-19 3:28 ` Eric Biggers
2020-02-19 3:47 ` Matthew Wilcox
2020-02-19 3:55 ` Eric Biggers
2020-02-17 18:45 ` [PATCH v6 11/19] btrfs: Convert from readpages to readahead Matthew Wilcox
2020-02-18 6:57 ` Dave Chinner
2020-02-18 21:12 ` Matthew Wilcox
2020-02-19 1:23 ` Dave Chinner
2020-02-17 18:46 ` [PATCH v6 11/16] erofs: Convert compressed files " Matthew Wilcox
2020-02-19 2:34 ` Gao Xiang
2020-02-17 18:46 ` [PATCH v6 12/19] erofs: Convert uncompressed " Matthew Wilcox
2020-02-19 2:39 ` Gao Xiang
2020-02-19 3:04 ` Dave Chinner
2020-02-17 18:46 ` [PATCH v6 12/16] ext4: Convert " Matthew Wilcox
2020-02-17 18:46 ` [PATCH v6 13/19] erofs: Convert compressed files " Matthew Wilcox
2020-02-19 3:08 ` Dave Chinner
2020-02-17 18:46 ` [PATCH v6 13/16] f2fs: Convert " Matthew Wilcox
2020-02-17 18:46 ` [PATCH v6 14/19] ext4: " Matthew Wilcox
2020-02-19 3:16 ` Dave Chinner
2020-02-19 3:29 ` Eric Biggers
2020-02-17 18:46 ` [PATCH v6 14/16] fuse: " Matthew Wilcox
2020-02-17 18:46 ` [PATCH v6 15/19] f2fs: " Matthew Wilcox
2020-02-17 18:46 ` [PATCH v6 15/16] iomap: " Matthew Wilcox
2020-02-17 18:46 ` [PATCH v6 16/19] fuse: " Matthew Wilcox
2020-02-19 3:22 ` Dave Chinner
2020-02-17 18:46 ` Matthew Wilcox [this message]
2020-02-17 18:46 ` [PATCH v6 17/19] iomap: Restructure iomap_readpages_actor Matthew Wilcox
2020-02-19 3:17 ` John Hubbard
2020-02-19 5:35 ` Matthew Wilcox
2020-02-19 3:29 ` Dave Chinner
2020-02-19 6:04 ` Matthew Wilcox
2020-02-19 6:40 ` Dave Chinner
2020-02-19 17:06 ` Matthew Wilcox
2020-02-17 18:46 ` [PATCH v6 18/19] iomap: Convert from readpages to readahead Matthew Wilcox
2020-02-19 3:40 ` Dave Chinner
2020-02-17 18:46 ` [PATCH v6 19/19] mm: Use memalloc_nofs_save in readahead path Matthew Wilcox
2020-02-19 3:43 ` Dave Chinner
2020-02-19 5:22 ` Matthew Wilcox
2020-02-17 18:48 ` [PATCH v6 00/19] Change readahead API Matthew Wilcox
2020-02-18 4:56 ` Dave Chinner
2020-02-18 13:42 ` Matthew Wilcox
2020-02-18 21:26 ` Dave Chinner
2020-02-19 3:45 ` Dave Chinner
2020-02-19 3:48 ` Matthew Wilcox
2020-02-19 3:57 ` Dave Chinner
2020-02-18 20:49 ` John Hubbard
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