forked from luck/tmp_suning_uos_patched
547c556f4d
ext4_writepages() on an encrypted file has to encrypt the data, but it
can't modify the pagecache pages in-place, so it encrypts the data into
bounce pages and writes those instead. All bounce pages are allocated
from a mempool using GFP_NOFS.
This is not correct use of a mempool, and it can deadlock. This is
because GFP_NOFS includes __GFP_DIRECT_RECLAIM, which enables the "never
fail" mode for mempool_alloc() where a failed allocation will fall back
to waiting for one of the preallocated elements in the pool.
But since this mode is used for all a bio's pages and not just the
first, it can deadlock waiting for pages already in the bio to be freed.
This deadlock can be reproduced by patching mempool_alloc() to pretend
that pool->alloc() always fails (so that it always falls back to the
preallocations), and then creating an encrypted file of size > 128 KiB.
Fix it by only using GFP_NOFS for the first page in the bio. For
subsequent pages just use GFP_NOWAIT, and if any of those fail, just
submit the bio and start a new one.
This will need to be fixed in f2fs too, but that's less straightforward.
Fixes:
|
||
|---|---|---|
| .. | ||
| acl.c | ||
| acl.h | ||
| balloc.c | ||
| bitmap.c | ||
| block_validity.c | ||
| dir.c | ||
| ext4_extents.h | ||
| ext4_jbd2.c | ||
| ext4_jbd2.h | ||
| ext4.h | ||
| extents_status.c | ||
| extents_status.h | ||
| extents.c | ||
| file.c | ||
| fsmap.c | ||
| fsmap.h | ||
| fsync.c | ||
| hash.c | ||
| ialloc.c | ||
| indirect.c | ||
| inline.c | ||
| inode-test.c | ||
| inode.c | ||
| ioctl.c | ||
| Kconfig | ||
| Makefile | ||
| mballoc.c | ||
| mballoc.h | ||
| migrate.c | ||
| mmp.c | ||
| move_extent.c | ||
| namei.c | ||
| page-io.c | ||
| readpage.c | ||
| resize.c | ||
| super.c | ||
| symlink.c | ||
| sysfs.c | ||
| truncate.h | ||
| verity.c | ||
| xattr_security.c | ||
| xattr_trusted.c | ||
| xattr_user.c | ||
| xattr.c | ||
| xattr.h | ||