From: Hugh Dickins <hughd@google.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>,
Vasily Gorbik <gor@linux.ibm.com>,
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>,
Yang Shi <shy828301@gmail.com>,
Mel Gorman <mgorman@techsingularity.net>,
Peter Xu <peterx@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Will Deacon <will@kernel.org>, Yu Zhao <yuzhao@google.com>,
Alistair Popple <apopple@nvidia.com>,
Ralph Campbell <rcampbell@nvidia.com>,
Ira Weiny <ira.weiny@intel.com>,
Steven Price <steven.price@arm.com>,
SeongJae Park <sj@kernel.org>,
Lorenzo Stoakes <lstoakes@gmail.com>,
Huang Ying <ying.huang@intel.com>,
Naoya Horiguchi <naoya.horiguchi@nec.com>,
Christophe Leroy <christophe.leroy@csgroup.eu>,
Zack Rusin <zackr@vmware.com>, Jason Gunthorpe <jgg@ziepe.ca>,
Axel Rasmussen <axelrasmussen@google.com>,
Anshuman Khandual <anshuman.khandual@arm.com>,
Pasha Tatashin <pasha.tatashin@soleen.com>,
Miaohe Lin <linmiaohe@huawei.com>,
Minchan Kim <minchan@kernel.org>,
Christoph Hellwig <hch@infradead.org>, Song Liu <song@kernel.org>,
Thomas Hellstrom <thomas.hellstrom@linux.intel.com>,
Russell King <linux@armlinux.org.uk>,
"David S. Miller" <davem@davemloft.net>,
Michael Ellerman <mpe@ellerman.id.au>,
"Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.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>,
Jann Horn <jannh@google.com>,
Vishal Moola <vishal.moola@gmail.com>,
Vlastimil Babka <vbabka@suse.cz>,
linux-arm-kernel@lists.infradead.org, sparclinux@vger.kernel.org,
linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: [PATCH v2 04/12] powerpc: assert_pte_locked() use pte_offset_map_nolock()
Date: Tue, 20 Jun 2023 00:45:26 -0700 (PDT) [thread overview]
Message-ID: <7ae6836b-b612-23f1-63e0-babda6e96e2c@google.com> (raw)
In-Reply-To: <54cb04f-3762-987f-8294-91dafd8ebfb0@google.com>
Instead of pte_lockptr(), use the recently added pte_offset_map_nolock()
in assert_pte_locked(). BUG if pte_offset_map_nolock() fails: this is
stricter than the previous implementation, which skipped when pmd_none()
(with a comment on khugepaged collapse transitions): but wouldn't we want
to know, if an assert_pte_locked() caller can be racing such transitions?
This mod might cause new crashes: which either expose my ignorance, or
indicate issues to be fixed, or limit the usage of assert_pte_locked().
Signed-off-by: Hugh Dickins <hughd@google.com>
---
arch/powerpc/mm/pgtable.c | 16 ++++++----------
1 file changed, 6 insertions(+), 10 deletions(-)
diff --git a/arch/powerpc/mm/pgtable.c b/arch/powerpc/mm/pgtable.c
index cb2dcdb18f8e..16b061af86d7 100644
--- a/arch/powerpc/mm/pgtable.c
+++ b/arch/powerpc/mm/pgtable.c
@@ -311,6 +311,8 @@ void assert_pte_locked(struct mm_struct *mm, unsigned long addr)
p4d_t *p4d;
pud_t *pud;
pmd_t *pmd;
+ pte_t *pte;
+ spinlock_t *ptl;
if (mm == &init_mm)
return;
@@ -321,16 +323,10 @@ void assert_pte_locked(struct mm_struct *mm, unsigned long addr)
pud = pud_offset(p4d, addr);
BUG_ON(pud_none(*pud));
pmd = pmd_offset(pud, addr);
- /*
- * khugepaged to collapse normal pages to hugepage, first set
- * pmd to none to force page fault/gup to take mmap_lock. After
- * pmd is set to none, we do a pte_clear which does this assertion
- * so if we find pmd none, return.
- */
- if (pmd_none(*pmd))
- return;
- BUG_ON(!pmd_present(*pmd));
- assert_spin_locked(pte_lockptr(mm, pmd));
+ pte = pte_offset_map_nolock(mm, pmd, addr, &ptl);
+ BUG_ON(!pte);
+ assert_spin_locked(ptl);
+ pte_unmap(pte);
}
#endif /* CONFIG_DEBUG_VM */
--
2.35.3
next prev parent reply other threads:[~2023-06-20 7:46 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-20 7:35 [PATCH v2 00/12] mm: free retracted page table by RCU Hugh Dickins
2023-06-20 7:40 ` [PATCH v2 01/12] mm/pgtable: add rcu_read_lock() and rcu_read_unlock()s Hugh Dickins
2023-06-20 7:42 ` [PATCH v2 02/12] mm/pgtable: add PAE safety to __pte_offset_map() Hugh Dickins
2023-06-20 7:43 ` [PATCH v2 03/12] arm: adjust_pte() use pte_offset_map_nolock() Hugh Dickins
2023-06-20 7:45 ` Hugh Dickins [this message]
2023-06-20 7:47 ` [PATCH v2 05/12] powerpc: add pte_free_defer() for pgtables sharing page Hugh Dickins
2023-06-20 11:45 ` Jason Gunthorpe
2023-06-20 19:54 ` Hugh Dickins
2023-06-20 23:52 ` Jason Gunthorpe
2023-06-22 2:36 ` Hugh Dickins
2023-06-27 17:01 ` Jason Gunthorpe
2023-06-27 20:53 ` Hugh Dickins
2023-06-20 7:49 ` [PATCH v2 06/12] sparc: add pte_free_defer() for pte_t *pgtable_t Hugh Dickins
2023-06-20 7:51 ` [PATCH v2 07/12] s390: add pte_free_defer() for pgtables sharing page Hugh Dickins
2023-06-28 19:16 ` Gerald Schaefer
2023-06-29 5:08 ` Hugh Dickins
2023-06-29 15:22 ` Jason Gunthorpe
2023-06-29 15:56 ` Gerald Schaefer
2023-06-30 6:00 ` Hugh Dickins
2023-07-02 4:32 ` Hugh Dickins
2023-07-04 13:40 ` Alexander Gordeev
2023-07-04 16:03 ` Hugh Dickins
2023-07-04 15:19 ` Gerald Schaefer
2023-07-04 17:03 ` Hugh Dickins
2023-07-05 12:55 ` Gerald Schaefer
2023-07-06 1:20 ` Hugh Dickins
2023-07-06 15:02 ` Gerald Schaefer
2023-07-06 19:45 ` Hugh Dickins
2023-07-10 17:21 ` Jason Gunthorpe
2023-07-05 6:46 ` Alexander Gordeev
2023-07-06 0:52 ` Hugh Dickins
2023-07-07 14:37 ` Gerald Schaefer
2023-07-03 16:10 ` Gerald Schaefer
2023-06-29 13:59 ` Alexander Gordeev
2023-06-29 15:43 ` Gerald Schaefer
2023-06-30 13:38 ` Claudio Imbrenda
2023-06-30 15:28 ` Hugh Dickins
2023-06-30 16:25 ` Claudio Imbrenda
2023-06-30 19:22 ` Hugh Dickins
2023-07-03 11:00 ` Claudio Imbrenda
2023-07-03 21:29 ` Jason Gunthorpe
2023-06-20 7:53 ` [PATCH v2 08/12] mm/pgtable: add pte_free_defer() for pgtable as page Hugh Dickins
2023-06-20 7:54 ` [PATCH v2 09/12] mm/khugepaged: retract_page_tables() without mmap or vma lock Hugh Dickins
2023-06-20 7:56 ` [PATCH v2 10/12] mm/khugepaged: collapse_pte_mapped_thp() with mmap_read_lock() Hugh Dickins
2023-06-20 8:04 ` [PATCH mm " Hugh Dickins
2023-06-20 7:58 ` [PATCH v2 11/12] mm/khugepaged: delete khugepaged_collapse_pte_mapped_thps() Hugh Dickins
2023-06-20 7:59 ` [PATCH v2 12/12] mm: delete mmap_write_trylock() and vma_try_start_write() Hugh Dickins
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