From: Hugh Dickins <hughd@google.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>,
Mike Rapoport <rppt@kernel.org>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Matthew Wilcox <willy@infradead.org>,
David Hildenbrand <david@redhat.com>,
Suren Baghdasaryan <surenb@google.com>,
Qi Zheng <zhengqi.arch@bytedance.com>,
Peter Zijlstra <peterz@infradead.org>,
Russell King <linux@armlinux.org.uk>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Geert Uytterhoeven <geert@linux-m68k.org>,
Greg Ungerer <gerg@linux-m68k.org>,
Michal Simek <monstr@monstr.eu>,
Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
Helge Deller <deller@gmx.de>,
John David Anglin <dave.anglin@bell.net>,
"Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>,
Michael Ellerman <mpe@ellerman.id.au>,
Alexandre Ghiti <alexghiti@rivosinc.com>,
Palmer Dabbelt <palmer@dabbelt.com>,
Heiko Carstens <hca@linux.ibm.com>,
Christian Borntraeger <borntraeger@linux.ibm.com>,
Claudio Imbrenda <imbrenda@linux.ibm.com>,
Alexander Gordeev <agordeev@linux.ibm.com>,
John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>,
"David S. Miller" <davem@davemloft.net>,
Chris Zankel <chris@zankel.net>,
Max Filippov <jcmvbkbc@gmail.com>,
x86@kernel.org, linux-arm-kernel@lists.infradead.org,
linux-ia64@vger.kernel.org, linux-m68k@lists.linux-m68k.org,
linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org,
linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org,
linux-s390@vger.kernel.org, linux-sh@vger.kernel.org,
sparclinux@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org
Subject: [PATCH v2 15/23] s390: allow pte_offset_map_lock() to fail
Date: Thu, 8 Jun 2023 12:27:22 -0700 (PDT) [thread overview]
Message-ID: <3ff29363-336a-9733-12a1-5c31a45c8aeb@google.com> (raw)
In-Reply-To: <a4963be9-7aa6-350-66d0-2ba843e1af44@google.com>
In rare transient cases, not yet made possible, pte_offset_map() and
pte_offset_map_lock() may not find a page table: handle appropriately.
Add comment on mm's contract with s390 above __zap_zero_pages(),
and fix old comment there: must be called after THP was disabled.
Signed-off-by: Hugh Dickins <hughd@google.com>
---
arch/s390/kernel/uv.c | 2 ++
arch/s390/mm/gmap.c | 9 ++++++++-
arch/s390/mm/pgtable.c | 12 +++++++++---
3 files changed, 19 insertions(+), 4 deletions(-)
diff --git a/arch/s390/kernel/uv.c b/arch/s390/kernel/uv.c
index cb2ee06df286..3c62d1b218b1 100644
--- a/arch/s390/kernel/uv.c
+++ b/arch/s390/kernel/uv.c
@@ -294,6 +294,8 @@ int gmap_make_secure(struct gmap *gmap, unsigned long gaddr, void *uvcb)
rc = -ENXIO;
ptep = get_locked_pte(gmap->mm, uaddr, &ptelock);
+ if (!ptep)
+ goto out;
if (pte_present(*ptep) && !(pte_val(*ptep) & _PAGE_INVALID) && pte_write(*ptep)) {
page = pte_page(*ptep);
rc = -EAGAIN;
diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c
index dc90d1eb0d55..3a2a31a15ea8 100644
--- a/arch/s390/mm/gmap.c
+++ b/arch/s390/mm/gmap.c
@@ -2537,7 +2537,12 @@ static inline void thp_split_mm(struct mm_struct *mm)
* Remove all empty zero pages from the mapping for lazy refaulting
* - This must be called after mm->context.has_pgste is set, to avoid
* future creation of zero pages
- * - This must be called after THP was enabled
+ * - This must be called after THP was disabled.
+ *
+ * mm contracts with s390, that even if mm were to remove a page table,
+ * racing with the loop below and so causing pte_offset_map_lock() to fail,
+ * it will never insert a page table containing empty zero pages once
+ * mm_forbids_zeropage(mm) i.e. mm->context.has_pgste is set.
*/
static int __zap_zero_pages(pmd_t *pmd, unsigned long start,
unsigned long end, struct mm_walk *walk)
@@ -2549,6 +2554,8 @@ static int __zap_zero_pages(pmd_t *pmd, unsigned long start,
spinlock_t *ptl;
ptep = pte_offset_map_lock(walk->mm, pmd, addr, &ptl);
+ if (!ptep)
+ break;
if (is_zero_pfn(pte_pfn(*ptep)))
ptep_xchg_direct(walk->mm, addr, ptep, __pte(_PAGE_INVALID));
pte_unmap_unlock(ptep, ptl);
diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c
index 6effb24de6d9..3bd2ab2a9a34 100644
--- a/arch/s390/mm/pgtable.c
+++ b/arch/s390/mm/pgtable.c
@@ -829,7 +829,7 @@ int set_guest_storage_key(struct mm_struct *mm, unsigned long addr,
default:
return -EFAULT;
}
-
+again:
ptl = pmd_lock(mm, pmdp);
if (!pmd_present(*pmdp)) {
spin_unlock(ptl);
@@ -850,6 +850,8 @@ int set_guest_storage_key(struct mm_struct *mm, unsigned long addr,
spin_unlock(ptl);
ptep = pte_offset_map_lock(mm, pmdp, addr, &ptl);
+ if (!ptep)
+ goto again;
new = old = pgste_get_lock(ptep);
pgste_val(new) &= ~(PGSTE_GR_BIT | PGSTE_GC_BIT |
PGSTE_ACC_BITS | PGSTE_FP_BIT);
@@ -938,7 +940,7 @@ int reset_guest_reference_bit(struct mm_struct *mm, unsigned long addr)
default:
return -EFAULT;
}
-
+again:
ptl = pmd_lock(mm, pmdp);
if (!pmd_present(*pmdp)) {
spin_unlock(ptl);
@@ -955,6 +957,8 @@ int reset_guest_reference_bit(struct mm_struct *mm, unsigned long addr)
spin_unlock(ptl);
ptep = pte_offset_map_lock(mm, pmdp, addr, &ptl);
+ if (!ptep)
+ goto again;
new = old = pgste_get_lock(ptep);
/* Reset guest reference bit only */
pgste_val(new) &= ~PGSTE_GR_BIT;
@@ -1000,7 +1004,7 @@ int get_guest_storage_key(struct mm_struct *mm, unsigned long addr,
default:
return -EFAULT;
}
-
+again:
ptl = pmd_lock(mm, pmdp);
if (!pmd_present(*pmdp)) {
spin_unlock(ptl);
@@ -1017,6 +1021,8 @@ int get_guest_storage_key(struct mm_struct *mm, unsigned long addr,
spin_unlock(ptl);
ptep = pte_offset_map_lock(mm, pmdp, addr, &ptl);
+ if (!ptep)
+ goto again;
pgste = pgste_get_lock(ptep);
*key = (pgste_val(pgste) & (PGSTE_ACC_BITS | PGSTE_FP_BIT)) >> 56;
paddr = pte_val(*ptep) & PAGE_MASK;
--
2.35.3
next prev parent reply other threads:[~2023-06-08 19:27 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-08 19:07 [PATCH v2 00/23] arch: allow pte_offset_map[_lock]() to fail Hugh Dickins
2023-06-08 19:10 ` [PATCH v2 01/23] arm: " Hugh Dickins
2023-06-08 19:11 ` [PATCH v2 02/23] arm64: allow pte_offset_map() " Hugh Dickins
2023-06-08 19:13 ` [PATCH v2 03/23] arm64/hugetlb: pte_alloc_huge() pte_offset_huge() Hugh Dickins
2023-06-08 19:14 ` [PATCH v2 04/23] ia64/hugetlb: " Hugh Dickins
2023-06-08 19:15 ` [PATCH v2 05/23] m68k: allow pte_offset_map[_lock]() to fail Hugh Dickins
2023-06-08 19:16 ` [PATCH v2 06/23] microblaze: allow pte_offset_map() " Hugh Dickins
2023-06-08 19:17 ` [PATCH v2 07/23] mips: update_mmu_cache() can replace __update_tlb() Hugh Dickins
2023-06-09 8:08 ` [PATCH v2 07/23 fix] mips: update_mmu_cache() can replace __update_tlb(): fix Hugh Dickins
2023-06-14 23:17 ` [PATCH v2 07/23] mips: update_mmu_cache() can replace __update_tlb() Nathan Chancellor
2023-06-15 0:26 ` Hugh Dickins
2023-06-15 5:43 ` Hugh Dickins
2023-06-15 15:50 ` Nathan Chancellor
2023-06-15 21:22 ` Hugh Dickins
2023-06-15 23:02 ` [PATCH v2 07/23 replacement] mips: add pte_unmap() to balance pte_offset_map() Hugh Dickins
2023-06-17 3:54 ` Yu Zhao
2023-06-18 20:57 ` Yu Zhao
2023-06-15 22:07 ` [PATCH v2 07/23] mips: update_mmu_cache() can replace __update_tlb() Yu Zhao
2023-06-08 19:18 ` [PATCH v2 08/23] parisc: add pte_unmap() to balance get_ptep() Hugh Dickins
2023-06-19 3:55 ` Helge Deller
2023-06-08 19:20 ` [PATCH v2 09/23] parisc: unmap_uncached_pte() use pte_offset_kernel() Hugh Dickins
2023-06-08 19:21 ` [PATCH v2 10/23] parisc/hugetlb: pte_alloc_huge() pte_offset_huge() Hugh Dickins
2023-06-08 19:22 ` [PATCH v2 11/23] powerpc: kvmppc_unmap_free_pmd() pte_offset_kernel() Hugh Dickins
2023-06-08 19:23 ` [PATCH v2 12/23] powerpc: allow pte_offset_map[_lock]() to fail Hugh Dickins
2023-06-08 19:24 ` [PATCH v2 13/23] powerpc/hugetlb: pte_alloc_huge() Hugh Dickins
2023-06-08 19:25 ` [PATCH v2 14/23] riscv/hugetlb: pte_alloc_huge() pte_offset_huge() Hugh Dickins
2023-06-08 19:27 ` Hugh Dickins [this message]
2023-06-13 11:45 ` [PATCH v2 15/23] s390: allow pte_offset_map_lock() to fail Claudio Imbrenda
2023-06-08 19:29 ` [PATCH v2 16/23] s390: gmap use pte_unmap_unlock() not spin_unlock() Hugh Dickins
2023-06-08 19:30 ` [PATCH v2 17/23] sh/hugetlb: pte_alloc_huge() pte_offset_huge() Hugh Dickins
2023-06-08 19:31 ` [PATCH v2 18/23] sparc/hugetlb: " Hugh Dickins
2023-06-08 19:32 ` [PATCH v2 19/23] sparc: allow pte_offset_map() to fail Hugh Dickins
2023-06-08 19:33 ` [PATCH v2 20/23] sparc: iounit and iommu use pte_offset_kernel() Hugh Dickins
2023-06-08 19:35 ` [PATCH v2 21/23] x86: Allow get_locked_pte() to fail Hugh Dickins
2023-06-08 19:36 ` [PATCH v2 22/23] x86: sme_populate_pgd() use pte_offset_kernel() Hugh Dickins
2023-06-08 19:37 ` [PATCH v2 23/23] xtensa: add pte_unmap() to balance pte_offset_map() Hugh Dickins
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