This is a note to let you know that I've just added the patch titled
fs/proc/task_mmu: move mmu notification mechanism inside mm lock
to the 6.7-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
fs-proc-task_mmu-move-mmu-notification-mechanism-inside-mm-lock.patch
and it can be found in the queue-6.7 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 4cccb6221cae6d020270606b9e52b1678fc8b71a Mon Sep 17 00:00:00 2001
From: Muhammad Usama Anjum <usama.anjum@xxxxxxxxxxxxx>
Date: Tue, 9 Jan 2024 16:24:42 +0500
Subject: fs/proc/task_mmu: move mmu notification mechanism inside mm lock
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
From: Muhammad Usama Anjum <usama.anjum@xxxxxxxxxxxxx>
commit 4cccb6221cae6d020270606b9e52b1678fc8b71a upstream.
Move mmu notification mechanism inside mm lock to prevent race condition
in other components which depend on it. The notifier will invalidate
memory range. Depending upon the number of iterations, different memory
ranges would be invalidated.
The following warning would be removed by this patch:
WARNING: CPU: 0 PID: 5067 at arch/x86/kvm/../../../virt/kvm/kvm_main.c:734 kvm_mmu_notifier_change_pte+0x860/0x960 arch/x86/kvm/../../../virt/kvm/kvm_main.c:734
There is no behavioural and performance change with this patch when
there is no component registered with the mmu notifier.
[akpm@xxxxxxxxxxxxxxxxxxxx: narrow the scope of `range', per Sean]
Link: https://lkml.kernel.org/r/20240109112445.590736-1-usama.anjum@xxxxxxxxxxxxx
Fixes: 52526ca7fdb9 ("fs/proc/task_mmu: implement IOCTL to get and optionally clear info about PTEs")
Signed-off-by: Muhammad Usama Anjum <usama.anjum@xxxxxxxxxxxxx>
Reported-by: syzbot+81227d2bd69e9dedb802@xxxxxxxxxxxxxxxxxxxxxxxxx
Link: https://lore.kernel.org/all/000000000000f6d051060c6785bc@xxxxxxxxxx/
Reviewed-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Cc: Andrei Vagin <avagin@xxxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
Cc: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
Cc: Michał Mirosław <mirq-linux@xxxxxxxxxxxx>
Cc: Peter Xu <peterx@xxxxxxxxxx>
Cc: Ryan Roberts <ryan.roberts@xxxxxxx>
Cc: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx>
Cc: Suren Baghdasaryan <surenb@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/proc/task_mmu.c | 24 +++++++++++++-----------
1 file changed, 13 insertions(+), 11 deletions(-)
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -2415,7 +2415,6 @@ static long pagemap_scan_flush_buffer(st
static long do_pagemap_scan(struct mm_struct *mm, unsigned long uarg)
{
- struct mmu_notifier_range range;
struct pagemap_scan_private p = {0};
unsigned long walk_start;
size_t n_ranges_out = 0;
@@ -2431,15 +2430,9 @@ static long do_pagemap_scan(struct mm_st
if (ret)
return ret;
- /* Protection change for the range is going to happen. */
- if (p.arg.flags & PM_SCAN_WP_MATCHING) {
- mmu_notifier_range_init(&range, MMU_NOTIFY_PROTECTION_VMA, 0,
- mm, p.arg.start, p.arg.end);
- mmu_notifier_invalidate_range_start(&range);
- }
-
for (walk_start = p.arg.start; walk_start < p.arg.end;
walk_start = p.arg.walk_end) {
+ struct mmu_notifier_range range;
long n_out;
if (fatal_signal_pending(current)) {
@@ -2450,8 +2443,20 @@ static long do_pagemap_scan(struct mm_st
ret = mmap_read_lock_killable(mm);
if (ret)
break;
+
+ /* Protection change for the range is going to happen. */
+ if (p.arg.flags & PM_SCAN_WP_MATCHING) {
+ mmu_notifier_range_init(&range, MMU_NOTIFY_PROTECTION_VMA, 0,
+ mm, walk_start, p.arg.end);
+ mmu_notifier_invalidate_range_start(&range);
+ }
+
ret = walk_page_range(mm, walk_start, p.arg.end,
&pagemap_scan_ops, &p);
+
+ if (p.arg.flags & PM_SCAN_WP_MATCHING)
+ mmu_notifier_invalidate_range_end(&range);
+
mmap_read_unlock(mm);
n_out = pagemap_scan_flush_buffer(&p);
@@ -2477,9 +2482,6 @@ static long do_pagemap_scan(struct mm_st
if (pagemap_scan_writeback_args(&p.arg, uarg))
ret = -EFAULT;
- if (p.arg.flags & PM_SCAN_WP_MATCHING)
- mmu_notifier_invalidate_range_end(&range);
-
kfree(p.vec_buf);
return ret;
}
Patches currently in stable-queue which might be from usama.anjum@xxxxxxxxxxxxx are
queue-6.7/fs-proc-task_mmu-move-mmu-notification-mechanism-inside-mm-lock.patch
