diff options
| -rw-r--r-- | mm/readahead.c | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/mm/readahead.c b/mm/readahead.c index 73cb59ed5cff..3c9a8dd7c56c 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" @@ -186,6 +187,18 @@ void page_cache_readahead_unbounded(struct address_space *mapping, unsigned long i; /* + * 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. */ for (i = 0; i < nr_to_read; i++) { @@ -229,6 +242,7 @@ void page_cache_readahead_unbounded(struct address_space *mapping, * will then handle the error. */ read_pages(&rac, &page_pool, false); + memalloc_nofs_restore(nofs); } EXPORT_SYMBOL_GPL(page_cache_readahead_unbounded); |