The patch titled
Subject: mm: userfaultfd: remove stale comment about core dump locking
has been added to the -mm mm-unstable branch. Its filename is
mm-userfaultfd-remove-stale-comment-about-core-dump-locking.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-userfaultfd-remove-stale-comment-about-core-dump-locking.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Jann Horn <jannh@xxxxxxxxxx>
Subject: mm: userfaultfd: remove stale comment about core dump locking
Date: Tue, 15 Aug 2023 23:22:16 +0200
Since commit 7f3bfab52cab ("mm/gup: take mmap_lock in get_dump_page()"),
which landed in v5.10, core dumping doesn't enter fault handling without
holding the mmap_lock anymore. Remove the stale parts of the comments,
but leave the behavior as-is - letting core dumping block on userfault
handling would be a bad idea and could lead to deadlocks if the dumping
process was handling its own userfaults.
Link: https://lkml.kernel.org/r/20230815212216.264445-1-jannh@xxxxxxxxxx
Signed-off-by: Jann Horn <jannh@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/userfaultfd.c | 6 +-----
1 file changed, 1 insertion(+), 5 deletions(-)
--- a/fs/userfaultfd.c~mm-userfaultfd-remove-stale-comment-about-core-dump-locking
+++ a/fs/userfaultfd.c
@@ -428,15 +428,11 @@ vm_fault_t handle_userfault(struct vm_fa
* FOLL_DUMP case, anon memory also checks for FOLL_DUMP with
* the no_page_table() helper in follow_page_mask(), but the
* shmem_vm_ops->fault method is invoked even during
- * coredumping without mmap_lock and it ends up here.
+ * coredumping and it ends up here.
*/
if (current->flags & (PF_EXITING|PF_DUMPCORE))
goto out;
- /*
- * Coredumping runs without mmap_lock so we can only check that
- * the mmap_lock is held, if PF_DUMPCORE was not set.
- */
assert_fault_locked(vmf);
ctx = vma->vm_userfaultfd_ctx.ctx;
_
Patches currently in -mm which might be from jannh@xxxxxxxxxx are
mm-userfaultfd-remove-stale-comment-about-core-dump-locking.patch
