accel/amdxdna: Fix race between unmap and free BO

Browse source

A userspace process can concurrently trigger an unmap, which queues
hmm_unreg_work, and free BO. If amdxdna_hmm_unreg_work() executes
list_del(&mapp->node) and is preempted before calling amdxdna_umap_put(),
amdxdna_hmm_unregister_all() can fail to find the mapping in the list
and return without calling cancel_work_sync(). This allows object
destruction to proceed while the worker still holds a pointer to the BO
in the umap structure.

Moving the work item from struct amdxdna_umap to struct amdxdna_gem_obj.
The worker no longer holds a pointer to an individual mapping, so there
is no longer a window where the umap has been unlinked from umap_list but
work is still pending against it. The work item now lives in the BO
itself, so use a single cancel_work_sync() in the free path to drain the
work.

Fixes: 445d209104 ("accel/amdxdna: Fix unexpected wait when flushing notifier_wq")
Reviewed-by: Max Zhen <max.zhen@amd.com>
Signed-off-by: Lizhi Hou <lizhi.hou@amd.com>
Link: https://patch.msgid.link/20260917154824.1872220-1-lizhi.hou@amd.com

...

This commit is contained in:

Lizhi Hou 2026-09-17 08:48:24 -07:00

parent 5eee433b5c

commit ac18f34f59

2 changed files with 42 additions and 56 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

95

drivers/accel/amdxdna/amdxdna_gem.c

View file

3

drivers/accel/amdxdna/amdxdna_gem.h

View file