From 004a9a38e20da6eb88fbfb7eeff0f3dd8a01776a Mon Sep 17 00:00:00 2001 From: Jann Horn Date: Tue, 15 Aug 2023 23:22:16 +0200 Subject: [PATCH] mm: userfaultfd: remove stale comment about core dump locking 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@google.com Signed-off-by: Jann Horn Signed-off-by: Andrew Morton --- fs/userfaultfd.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-) diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c index 1091cb461747..56eaae9dac1a 100644 --- a/fs/userfaultfd.c +++ b/fs/userfaultfd.c @@ -428,15 +428,11 @@ vm_fault_t handle_userfault(struct vm_fault *vmf, unsigned long reason) * 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;