+ mm-fix-failure-to-unmap-pte-on-highmem-systems.patch added to mm-unstable branch

+ mm-fix-failure-to-unmap-pte-on-highmem-systems.patch added to mm-unstable branch

[Andrew Morton]

The patch titled
     Subject: mm: fix failure to unmap pte on highmem systems
has been added to the -mm mm-unstable branch.  Its filename is
     mm-fix-failure-to-unmap-pte-on-highmem-systems.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-fix-failure-to-unmap-pte-on-highmem-systems.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: Ryan Roberts <ryan.roberts@arm.com>
Subject: mm: fix failure to unmap pte on highmem systems
Date: Fri, 2 Jun 2023 10:29:49 +0100

The loser of a race to service a pte for a device private entry in the
swap path previously unlocked the ptl, but failed to unmap the pte.  This
only affects highmem systems since unmapping a pte is a noop on
non-highmem systems.

Link: https://lkml.kernel.org/r/20230602092949.545577-5-ryan.roberts@arm.com
Fixes: 16ce101db85d ("mm/memory.c: fix race when faulting a device private page")
Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: SeongJae Park <sj@kernel.org>
Cc: Uladzislau Rezki (Sony) <urezki@gmail.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/memory.c |    6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

--- a/mm/memory.c~mm-fix-failure-to-unmap-pte-on-highmem-systems
+++ a/mm/memory.c
@@ -3729,10 +3729,8 @@ vm_fault_t do_swap_page(struct vm_fault
 			vmf->page = pfn_swap_entry_to_page(entry);
 			vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
 					vmf->address, &vmf->ptl);
-			if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte))) {
-				spin_unlock(vmf->ptl);
-				goto out;
-			}
+			if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte)))
+				goto unlock;
 
 			/*
 			 * Get a page reference while we know the page can't be
_

Patches currently in -mm which might be from ryan.roberts@arm.com are

mm-vmalloc-must-set-pte-via-arch-code.patch
mm-damon-ops-common-atomically-test-and-clear-young-on-ptes-and-pmds.patch
mm-damon-ops-common-refactor-to-use-ptepmdp_clear_young_notify.patch
mm-fix-failure-to-unmap-pte-on-highmem-systems.patch