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mm/page_vma_mapped: pte_offset_map_nolock() not pte_lockptr() 

map_pte() use pte_offset_map_nolock(), to make sure of the ptl belonging
to pte, even if pmd entry is then changed racily: page_vma_mapped_walk()
use that instead of getting pte_lockptr() later, or restart if map_pte()
found no page table.

Link: https://lkml.kernel.org/r/cba186e0-5ed7-e81b-6cd-dade4c33c248@google.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Song Liu <song@kernel.org>
Cc: Steven Price <steven.price@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Will Deacon <will@kernel.org>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: Zack Rusin <zackr@vmware.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Hugh Dickins 2023-06-08 18:15:43 -07:00 committed by Andrew Morton
parent 90f43b0a13
commit 2798bbe75b
1 changed files with 22 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

28
mm/page_vma_mapped.c
View File

@ -13,16 +13,28 @@ static inline bool not_found(struct page_vma_mapped_walk *pvmw)
return false;
}
static bool map_pte(struct page_vma_mapped_walk *pvmw)
static bool map_pte(struct page_vma_mapped_walk *pvmw, spinlock_t **ptlp)
{
if (pvmw->flags & PVMW_SYNC) {
/* Use the stricter lookup */
pvmw->pte = pte_offset_map_lock(pvmw->vma->vm_mm, pvmw->pmd,
pvmw->address, &pvmw->ptl);
return true;
*ptlp = pvmw->ptl;
return !!pvmw->pte;
}
pvmw->pte = pte_offset_map(pvmw->pmd, pvmw->address);
/*
* It is important to return the ptl corresponding to pte,
* in case *pvmw->pmd changes underneath us; so we need to
* return it even when choosing not to lock, in case caller
* proceeds to loop over next ptes, and finds a match later.
* Though, in most cases, page lock already protects this.
*/
pvmw->pte = pte_offset_map_nolock(pvmw->vma->vm_mm, pvmw->pmd,
pvmw->address, ptlp);
if (!pvmw->pte)
return false;
if (pvmw->flags & PVMW_MIGRATION) {
if (!is_swap_pte(*pvmw->pte))
return false;
@ -51,7 +63,7 @@ static bool map_pte(struct page_vma_mapped_walk *pvmw)
} else if (!pte_present(*pvmw->pte)) {
return false;
}
pvmw->ptl = pte_lockptr(pvmw->vma->vm_mm, pvmw->pmd);
pvmw->ptl = *ptlp;
spin_lock(pvmw->ptl);
return true;
}
@ -156,6 +168,7 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw)
struct vm_area_struct *vma = pvmw->vma;
struct mm_struct *mm = vma->vm_mm;
unsigned long end;
spinlock_t *ptl;
pgd_t *pgd;
p4d_t *p4d;
pud_t *pud;
@ -257,8 +270,11 @@ restart:
step_forward(pvmw, PMD_SIZE);
continue;
}
if (!map_pte(pvmw))
if (!map_pte(pvmw, &ptl)) {
if (!pvmw->pte)
goto restart;
goto next_pte;
}
this_pte:
if (check_pte(pvmw))
return true;
@ -281,7 +297,7 @@ next_pte:
} while (pte_none(*pvmw->pte));
if (!pvmw->ptl) {
pvmw->ptl = pte_lockptr(mm, pvmw->pmd);
pvmw->ptl = ptl;
spin_lock(pvmw->ptl);
}
goto this_pte;