The quilt patch titled
Subject: mm/userfaultfd: allow pte_offset_map_lock() to fail
has been removed from the -mm tree. Its filename was
mm-userfaultfd-allow-pte_offset_map_lock-to-fail.patch
This patch was dropped because it was merged into the mm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
------------------------------------------------------
From: Hugh Dickins <hughd@xxxxxxxxxx>
Subject: mm/userfaultfd: allow pte_offset_map_lock() to fail
Date: Thu, 8 Jun 2023 18:26:04 -0700 (PDT)
mfill_atomic_install_pte() and mfill_atomic_pte_zeropage() treat failed
pte_offset_map_lock() as -EAGAIN, which mfill_atomic() already returns to
user for a similar race.
Link: https://lkml.kernel.org/r/50cf3930-1bfa-4de9-a079-3da47b7ce17b@xxxxxxxxxx
Signed-off-by: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Alistair Popple <apopple@xxxxxxxxxx>
Cc: Anshuman Khandual <anshuman.khandual@xxxxxxx>
Cc: Axel Rasmussen <axelrasmussen@xxxxxxxxxx>
Cc: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: "Huang, Ying" <ying.huang@xxxxxxxxx>
Cc: Ira Weiny <ira.weiny@xxxxxxxxx>
Cc: Jason Gunthorpe <jgg@xxxxxxxx>
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Lorenzo Stoakes <lstoakes@xxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Cc: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: Mike Rapoport (IBM) <rppt@xxxxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Naoya Horiguchi <naoya.horiguchi@xxxxxxx>
Cc: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx>
Cc: Peter Xu <peterx@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx>
Cc: Ralph Campbell <rcampbell@xxxxxxxxxx>
Cc: Ryan Roberts <ryan.roberts@xxxxxxx>
Cc: SeongJae Park <sj@xxxxxxxxxx>
Cc: Song Liu <song@xxxxxxxxxx>
Cc: Steven Price <steven.price@xxxxxxx>
Cc: Suren Baghdasaryan <surenb@xxxxxxxxxx>
Cc: Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Cc: Yang Shi <shy828301@xxxxxxxxx>
Cc: Yu Zhao <yuzhao@xxxxxxxxxx>
Cc: Zack Rusin <zackr@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/userfaultfd.c | 8 ++++++++
1 file changed, 8 insertions(+)
--- a/mm/userfaultfd.c~mm-userfaultfd-allow-pte_offset_map_lock-to-fail
+++ a/mm/userfaultfd.c
@@ -76,7 +76,10 @@ int mfill_atomic_install_pte(pmd_t *dst_
if (flags & MFILL_ATOMIC_WP)
_dst_pte = pte_mkuffd_wp(_dst_pte);
+ ret = -EAGAIN;
dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl);
+ if (!dst_pte)
+ goto out;
if (vma_is_shmem(dst_vma)) {
/* serialize against truncate with the page table lock */
@@ -121,6 +124,7 @@ int mfill_atomic_install_pte(pmd_t *dst_
ret = 0;
out_unlock:
pte_unmap_unlock(dst_pte, ptl);
+out:
return ret;
}
@@ -212,7 +216,10 @@ static int mfill_atomic_pte_zeropage(pmd
_dst_pte = pte_mkspecial(pfn_pte(my_zero_pfn(dst_addr),
dst_vma->vm_page_prot));
+ ret = -EAGAIN;
dst_pte = pte_offset_map_lock(dst_vma->vm_mm, dst_pmd, dst_addr, &ptl);
+ if (!dst_pte)
+ goto out;
if (dst_vma->vm_file) {
/* the shmem MAP_PRIVATE case requires checking the i_size */
inode = dst_vma->vm_file->f_inode;
@@ -231,6 +238,7 @@ static int mfill_atomic_pte_zeropage(pmd
ret = 0;
out_unlock:
pte_unmap_unlock(dst_pte, ptl);
+out:
return ret;
}
_
Patches currently in -mm which might be from hughd@xxxxxxxxxx are
