The patch titled
Subject: userfaultfd: clear flag if remap event not enabled
has been added to the -mm tree. Its filename is
userfaultfd-clear-flag-if-remap-event-not-enabled.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/userfaultfd-clear-flag-if-remap-event-not-enabled.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/userfaultfd-clear-flag-if-remap-event-not-enabled.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Peter Xu <peterx@xxxxxxxxxx>
Subject: userfaultfd: clear flag if remap event not enabled
When the process being tracked does mremap() without
UFFD_FEATURE_EVENT_REMAP on the corresponding tracking uffd file handle,
we should not generate the remap event, and at the same time we should
clear all the uffd flags on the new VMA. Without this patch, we can still
have the VM_UFFD_MISSING|VM_UFFD_WP flags on the new VMA even the fault
handling process does not even know the existance of the VMA.
Link: http://lkml.kernel.org/r/20181211053409.20317-1-peterx@xxxxxxxxxx
Signed-off-by: Peter Xu <peterx@xxxxxxxxxx>
Reviewed-by: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Acked-by: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx>
Reviewed-by: William Kucharski <william.kucharski@xxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx>
Cc: Kirill A. Shutemov <kirill@xxxxxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Pavel Emelyanov <xemul@xxxxxxxxxxxxx>
Cc: Pravin Shedge <pravin.shedge4linux@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/userfaultfd.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
--- a/fs/userfaultfd.c~userfaultfd-clear-flag-if-remap-event-not-enabled
+++ a/fs/userfaultfd.c
@@ -735,10 +735,18 @@ void mremap_userfaultfd_prep(struct vm_a
struct userfaultfd_ctx *ctx;
ctx = vma->vm_userfaultfd_ctx.ctx;
- if (ctx && (ctx->features & UFFD_FEATURE_EVENT_REMAP)) {
+
+ if (!ctx)
+ return;
+
+ if (ctx->features & UFFD_FEATURE_EVENT_REMAP) {
vm_ctx->ctx = ctx;
userfaultfd_ctx_get(ctx);
WRITE_ONCE(ctx->mmap_changing, true);
+ } else {
+ /* Drop uffd context if remap feature not enabled */
+ vma->vm_userfaultfd_ctx = NULL_VM_UFFD_CTX;
+ vma->vm_flags &= ~(VM_UFFD_WP | VM_UFFD_MISSING);
}
}
_
Patches currently in -mm which might be from peterx@xxxxxxxxxx are
userfaultfd-clear-flag-if-remap-event-not-enabled.patch
