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| author | Lars Ellenberg <lars.ellenberg@linbit.com> | 2012-09-26 14:18:51 +0200 |
|---|---|---|
| committer | Philipp Reisner <philipp.reisner@linbit.com> | 2012-11-09 14:11:39 +0100 |
| commit | bc891c9ae3fb2848922e0f0da22fd7de0d58dc1b (patch) | |
| tree | 58353dfe6fb1257533959a56346b5d5a0a15ad4f /drivers/block | |
| parent | drbd: use list_move_tail instead of list_del/list_add_tail (diff) | |
| download | linux-bc891c9ae3fb2848922e0f0da22fd7de0d58dc1b.tar.xz linux-bc891c9ae3fb2848922e0f0da22fd7de0d58dc1b.zip | |
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>
Diffstat (limited to 'drivers/block')
| -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 4a076b2553e6..e502535d2c4d 100644 --- a/drivers/block/drbd/drbd_bitmap.c +++ b/drivers/block/drbd/drbd_bitmap.c @@ -388,14 +388,16 @@ 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 drbdsetup / - * netlink process. 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 dmsetup. */ bytes = sizeof(struct page *)*want; - new_pages = kmalloc(bytes, GFP_KERNEL); + new_pages = kmalloc(bytes, GFP_NOIO); if (!new_pages) { - new_pages = vmalloc(bytes); + new_pages = __vmalloc(bytes, + GFP_NOIO | __GFP_HIGHMEM, + PAGE_KERNEL); if (!new_pages) return NULL; vmalloced = 1; @@ -406,7 +408,7 @@ 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); |