From: Will Deacon <will@kernel.org>
To: linux-kernel@vger.kernel.org
Cc: sparclinux@vger.kernel.org, Will Deacon <will@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
"David S . Miller" <davem@davemloft.net>,
Guenter Roeck <linux@roeck-us.net>,
Mike Rapoport <rppt@kernel.org>,
kernel-team@android.com
Subject: [PATCH 3/3] sparc32: mm: Only call ctor()/dtor() functions for first and last user
Date: Tue, 26 May 2020 18:33:02 +0100 [thread overview]
Message-ID: <20200526173302.377-4-will@kernel.org> (raw)
In-Reply-To: <20200526173302.377-1-will@kernel.org>
The SRMMU page-table allocator allocates multiple PTE tables per page,
since they are only 1K in size. However, this means that calls to
pgtable_pte_page_{ctor,dtor}() must be serialised and performed only by
the first and last page-table allocation for the page respectively.
Use the page reference count to track how many PTE tables we have
allocated for a given page returned by the SRMMU allocator and only
call the ctor()/dtor() functions for the first and last user respectively.
Cc: David S. Miller <davem@davemloft.net>
Fixes: 8c8f3156dd40 ("sparc32: mm: Reduce allocation size for PMD and PTE tables")
Signed-off-by: Will Deacon <will@kernel.org>
---
arch/sparc/mm/srmmu.c | 14 +++++++++++---
1 file changed, 11 insertions(+), 3 deletions(-)
diff --git a/arch/sparc/mm/srmmu.c b/arch/sparc/mm/srmmu.c
index 589370a21b12..116d19a390f2 100644
--- a/arch/sparc/mm/srmmu.c
+++ b/arch/sparc/mm/srmmu.c
@@ -364,9 +364,13 @@ pgtable_t pte_alloc_one(struct mm_struct *mm)
if ((ptep = pte_alloc_one_kernel(mm)) == 0)
return NULL;
page = pfn_to_page(__nocache_pa((unsigned long)ptep) >> PAGE_SHIFT);
- if (!pgtable_pte_page_ctor(page)) {
- return NULL;
+ spin_lock(&mm->page_table_lock);
+ if (page_ref_inc_return(page) == 2 && !pgtable_pte_page_ctor(page)) {
+ page_ref_dec(page);
+ ptep = NULL;
}
+ spin_unlock(&mm->page_table_lock);
+
return ptep;
}
@@ -375,7 +379,11 @@ void pte_free(struct mm_struct *mm, pgtable_t ptep)
struct page *page;
page = pfn_to_page(__nocache_pa((unsigned long)ptep) >> PAGE_SHIFT);
- pgtable_pte_page_dtor(page);
+ spin_lock(&mm->page_table_lock);
+ if (page_ref_dec_return(page) == 1)
+ pgtable_pte_page_dtor(page);
+ spin_unlock(&mm->page_table_lock);
+
srmmu_free_nocache(ptep, SRMMU_PTE_TABLE_SIZE);
}
--
2.27.0.rc0.183.gde8f92d652-goog
next prev parent reply other threads:[~2020-05-26 17:33 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-26 17:32 [PATCH 0/3] sparc32 SRMMU fixes for SMP Will Deacon
2020-05-26 17:33 ` [PATCH 1/3] sparc32: mm: Don't try to free page-table pages if ctor() fails Will Deacon
2020-05-26 17:33 ` [PATCH 2/3] sparc32: mm: Disable SPLIT_PTLOCK_CPUS Will Deacon
2020-05-26 17:33 ` Will Deacon [this message]
2020-06-03 1:46 ` [PATCH 0/3] sparc32 SRMMU fixes for SMP David Miller
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