Re: [RFC PATCH RESEND 19/28] mm: disallow do_swap_page to handle page faults under VMA lock
From: Peter Xu <peterx@redhat.com>
Date: 2022-09-06 19:40:10
Also in:
linux-arm-kernel, linux-mm, lkml
On Thu, Sep 01, 2022 at 10:35:07AM -0700, Suren Baghdasaryan wrote:
quoted hunk ↗ jump to hunk
Due to the possibility of do_swap_page dropping mmap_lock, abort fault handling under VMA lock and retry holding mmap_lock. This can be handled more gracefully in the future. Signed-off-by: Suren Baghdasaryan <surenb@google.com> --- mm/memory.c | 5 +++++ 1 file changed, 5 insertions(+)diff --git a/mm/memory.c b/mm/memory.c index 9ac9944e8c62..29d2f49f922a 100644 --- a/mm/memory.c +++ b/mm/memory.c@@ -3738,6 +3738,11 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) vm_fault_t ret = 0; void *shadow = NULL; + if (vmf->flags & FAULT_FLAG_VMA_LOCK) { + ret = VM_FAULT_RETRY; + goto out; + } +
May want to fail early similarly for handle_userfault() too for similar reason. Thanks, -- Peter Xu