Commit d41df997 authored by Ryan Roberts's avatar Ryan Roberts Committed by Wupeng Ma
Browse files

mm: fix failure to unmap pte on highmem systems 

mainline inclusion
from mainline-v6.5-rc1
commit 3b65f437
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/IAQT9Q

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=3b65f437d9e8dd696a2b88e7afcd51385532ab35

--------------------------------

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: 16ce101d ("mm/memory.c: fix race when faulting a device private page")
Signed-off-by: default avatarRyan Roberts <ryan.roberts@arm.com>
Reviewed-by: default avatarZi Yan <ziy@nvidia.com>
Reviewed-by: default avatarMike Rapoport (IBM) <rppt@kernel.org>
Cc: Christoph Hellwig <hch@lst.de>
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>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarMa Wupeng <mawupeng1@huawei.com>
parent 5a1d9701

mm/memory.c

+2 −4
Original line number Diff line number Diff line
@@ -3424,10 +3424,8 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) 
			vmf->page = device_private_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