UbiquitousOS
/
OpenCloudOS-Kernel
mirror of https://gitee.com/OpenCloudOS/OpenCloudOS-Kernel.git
11
0
Fork 0
Code Issues Projects Releases Wiki Activity

mm: prevent userfaults to be handled under per-vma lock 

Due to the possibility of handle_userfault dropping mmap_lock, avoid fault
handling under VMA lock and retry holding mmap_lock.  This can be handled
more gracefully in the future.

Link: https://lkml.kernel.org/r/20230227173632.3292573-28-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Suggested-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Suren Baghdasaryan 2023-02-27 09:36:26 -08:00 committed by Andrew Morton
parent 17c05f18e5
commit 444eeb1743
1 changed files with 9 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
mm/memory.c
View File

@ -5266,6 +5266,15 @@ retry:
if (!vma_start_read(vma)) if (!vma_start_read(vma))
goto inval; goto inval;
/*
* Due to the possibility of userfault handler dropping mmap_lock, avoid
* it for now and fall back to page fault handling under mmap_lock.
*/
if (userfaultfd_armed(vma)) {
vma_end_read(vma);
goto inval;
}
/* Check since vm_start/vm_end might change before we lock the VMA */ /* Check since vm_start/vm_end might change before we lock the VMA */
if (unlikely(address < vma->vm_start || address >= vma->vm_end)) { if (unlikely(address < vma->vm_start || address >= vma->vm_end)) {
vma_end_read(vma); vma_end_read(vma);