Commit 20d9600c authored by David Dillow's avatar David Dillow Committed by Linus Torvalds

fs/direct-io.c: don't try to allocate more than BIO_MAX_PAGES in a bio

When using devices that support max_segments > BIO_MAX_PAGES (256), direct
IO tries to allocate a bio with more pages than allowed, which leads to an
oops in dio_bio_alloc().  Clamp the request to the supported maximum, and
change dio_bio_alloc() to reflect that bio_alloc() will always return a
bio when called with __GFP_WAIT and a valid number of vectors.

[ remove redundant BUG_ON()]
Signed-off-by: default avatarDavid Dillow <>
Reviewed-by: default avatarJeff Moyer <>
Cc: <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent 82478fb7
......@@ -325,12 +325,16 @@ void dio_end_io(struct bio *bio, int error)
static int
static void
dio_bio_alloc(struct dio *dio, struct block_device *bdev,
sector_t first_sector, int nr_vecs)
struct bio *bio;
* bio_alloc() is guaranteed to return a bio when called with
* __GFP_WAIT and we request a valid number of vectors.
bio = bio_alloc(GFP_KERNEL, nr_vecs);
bio->bi_bdev = bdev;
......@@ -342,7 +346,6 @@ dio_bio_alloc(struct dio *dio, struct block_device *bdev,
dio->bio = bio;
dio->logical_offset_in_bio = dio->cur_page_fs_offset;
return 0;
......@@ -583,8 +586,9 @@ static int dio_new_bio(struct dio *dio, sector_t start_sector)
goto out;
sector = start_sector << (dio->blkbits - 9);
nr_pages = min(dio->pages_in_io, bio_get_nr_vecs(dio->map_bh.b_bdev));
nr_pages = min(nr_pages, BIO_MAX_PAGES);
BUG_ON(nr_pages <= 0);
ret = dio_bio_alloc(dio, dio->map_bh.b_bdev, sector, nr_pages);
dio_bio_alloc(dio, dio->map_bh.b_bdev, sector, nr_pages);
dio->boundary = 0;
return ret;
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