diff options
| author | Lars Ellenberg <lars.ellenberg@linbit.com> | 2012-09-20 16:05:39 +0400 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2012-10-30 11:39:18 +0400 |
| commit | 0b143d4382b62db6738196caaefa793e5c0f6690 (patch) | |
| tree | 0163ab96980949c3bc6e578540e3fa7e95969b74 /drivers/block/drbd/drbd_bitmap.c | |
| parent | 7fb907c15fb8d0e10e72c8566a13f6defab3f484 (diff) | |
| download | linux-0b143d4382b62db6738196caaefa793e5c0f6690.tar.xz | |
drbd: fix potential deadlock during bitmap (re-)allocation
The former comment arguing that GFP_KERNEL was good enough was wrong: it
did not take resize into account at all, and assumed the only path
leading here was the normal attach on a still secondary device, so no
deadlock would be possible.
Both resize on a Primary, or attach on a diskless Primary,
could potentially deadlock.
drbd_bm_resize() is called while IO to the respective device is
suspended, so we must use GFP_NOIO to avoid potential deadlock.
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'drivers/block/drbd/drbd_bitmap.c')
| -rw-r--r-- | drivers/block/drbd/drbd_bitmap.c | 16 |
1 files changed, 9 insertions, 7 deletions
diff --git a/drivers/block/drbd/drbd_bitmap.c b/drivers/block/drbd/drbd_bitmap.c index d84566496746..dda4e384929e 100644 --- a/drivers/block/drbd/drbd_bitmap.c +++ b/drivers/block/drbd/drbd_bitmap.c @@ -373,14 +373,16 @@ static struct page **bm_realloc_pages(struct drbd_bitmap *b, unsigned long want) return old_pages; /* Trying kmalloc first, falling back to vmalloc. - * GFP_KERNEL is ok, as this is done when a lower level disk is - * "attached" to the drbd. Context is receiver thread or cqueue - * thread. As we have no disk yet, we are not in the IO path, - * not even the IO path of the peer. */ + * GFP_NOIO, as this is called while drbd IO is "suspended", + * and during resize or attach on diskless Primary, + * we must not block on IO to ourselves. + * Context is receiver thread or cqueue thread/dmsetup. */ bytes = sizeof(struct page *)*want; - new_pages = kzalloc(bytes, GFP_KERNEL); + new_pages = kzalloc(bytes, GFP_NOIO); if (!new_pages) { - new_pages = vzalloc(bytes); + new_pages = __vmalloc(bytes, + GFP_NOIO | __GFP_HIGHMEM | __GFP_ZERO, + PAGE_KERNEL); if (!new_pages) return NULL; vmalloced = 1; @@ -390,7 +392,7 @@ static struct page **bm_realloc_pages(struct drbd_bitmap *b, unsigned long want) for (i = 0; i < have; i++) new_pages[i] = old_pages[i]; for (; i < want; i++) { - page = alloc_page(GFP_HIGHUSER); + page = alloc_page(GFP_NOIO | __GFP_HIGHMEM); if (!page) { bm_free_pages(new_pages + have, i - have); bm_vk_free(new_pages, vmalloced); |