CVE-2026-64326

In the Linux kernel, the following vulnerability has been resolved:

block: skip sync_blockdev() on surprise removal in bdev_mark_dead()

bdev_mark_dead()'s @surprise == true means the device is already gone.

The filesystem callback fs_bdev_mark_dead() honours this and skips

sync_filesystem(), but the bare block device path (no ->mark_dead op)

lost its !surprise guard when the holder ->mark_dead callback was wired

up (see Fixes), and now calls sync_blockdev() unconditionally, which can

hang forever waiting on writeback that can no longer complete.

syzkaller hit this via nvme_reset_work()'s "I/O queues lost" path:

nvme_mark_namespaces_dead() -> blk_mark_disk_dead() ->

bdev_mark_dead(bdev, true) -> sync_blockdev() blocks in

folio_wait_writeback(), wedging the reset worker and every task waiting

on it.

Skip the sync on surprise removal, matching fs_bdev_mark_dead();

invalidate_bdev() still runs. Orderly removal (surprise == false) is

unchanged.

Found by FuzzNvme(Syzkaller with FEMU fuzzing framework).