From: David Hildenbrand david@redhat.com
mainline inclusion from mainline-v6.9-rc1 commit 0cf18e839f64fff9a58569cc9a596bf97310e044 category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I9CHB4 CVE: NA
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We don't need uptodate accessed/dirty bits, so in theory we could replace ptep_get_and_clear_full() by an optimized ptep_clear_full() function. Let's rely on the provided pte.
Further, there is no scenario where we would have to insert uffd-wp markers when zapping something that is not a normal page (i.e., zeropage). Add a sanity check to make sure this remains true.
should_zap_folio() no longer has to handle NULL pointers. This change replaces 2/3 "!page/!folio" checks by a single "!page" one.
Note that arch_check_zapped_pte() on x86-64 checks the HW-dirty bit to detect shadow stack entries. But for shadow stack entries, the HW dirty bit (in combination with non-writable PTEs) is set by software. So for the arch_check_zapped_pte() check, we don't have to sync against HW setting the HW dirty bit concurrently, it is always set.
Link: https://lkml.kernel.org/r/20240214204435.167852-3-david@redhat.com Signed-off-by: David Hildenbrand david@redhat.com Reviewed-by: Ryan Roberts ryan.roberts@arm.com Cc: Alexander Gordeev agordeev@linux.ibm.com Cc: Aneesh Kumar K.V aneesh.kumar@linux.ibm.com Cc: Arnd Bergmann arnd@arndb.de Cc: Catalin Marinas catalin.marinas@arm.com Cc: Christian Borntraeger borntraeger@linux.ibm.com Cc: Christophe Leroy christophe.leroy@csgroup.eu Cc: Heiko Carstens hca@linux.ibm.com Cc: Matthew Wilcox (Oracle) willy@infradead.org Cc: Michael Ellerman mpe@ellerman.id.au Cc: Michal Hocko mhocko@suse.com Cc: "Naveen N. Rao" naveen.n.rao@linux.ibm.com Cc: Nicholas Piggin npiggin@gmail.com Cc: Peter Zijlstra (Intel) peterz@infradead.org Cc: Sven Schnelle svens@linux.ibm.com Cc: Vasily Gorbik gor@linux.ibm.com Cc: Will Deacon will@kernel.org Cc: Yin Fengwei fengwei.yin@intel.com Signed-off-by: Andrew Morton akpm@linux-foundation.org (cherry picked from commit 0cf18e839f64fff9a58569cc9a596bf97310e044) Signed-off-by: Kefeng Wang wangkefeng.wang@huawei.com --- mm/memory.c | 22 +++++++++++----------- 1 file changed, 11 insertions(+), 11 deletions(-)
diff --git a/mm/memory.c b/mm/memory.c index 44dc030ae8a9..7ac5855b6e1c 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1500,10 +1500,6 @@ static inline bool should_zap_folio(struct zap_details *details, if (should_zap_cows(details)) return true;
- /* E.g. the caller passes NULL for the case of a zero folio */ - if (!folio) - return true; - /* Otherwise we should only zap non-anon folios */ return !folio_test_anon(folio); } @@ -1541,24 +1537,28 @@ static inline void zap_present_pte(struct mmu_gather *tlb, int *rss, bool *force_flush, bool *force_break) { struct mm_struct *mm = tlb->mm; - struct folio *folio = NULL; bool delay_rmap = false; + struct folio *folio; struct page *page;
page = vm_normal_page(vma, addr, ptent); - if (page) - folio = page_folio(page); + if (!page) { + /* We don't need up-to-date accessed/dirty bits. */ + ptep_get_and_clear_full(mm, addr, pte, tlb->fullmm); + arch_check_zapped_pte(vma, ptent); + tlb_remove_tlb_entry(tlb, pte, addr); + VM_WARN_ON_ONCE(userfaultfd_wp(vma)); + ksm_might_unmap_zero_page(mm, ptent); + return; + }
+ folio = page_folio(page); if (unlikely(!should_zap_folio(details, folio))) return; ptent = ptep_get_and_clear_full(mm, addr, pte, tlb->fullmm); arch_check_zapped_pte(vma, ptent); tlb_remove_tlb_entry(tlb, pte, addr); zap_install_uffd_wp_if_needed(vma, addr, pte, details, ptent); - if (unlikely(!page)) { - ksm_might_unmap_zero_page(mm, ptent); - return; - }
if (!folio_test_anon(folio)) { if (pte_dirty(ptent)) {