From: Song Liu <songliubraving@fb.com>
To: <linux-kernel@vger.kernel.org>, <linux-mm@kvack.org>
Cc: <kernel-team@fb.com>, Song Liu <songliubraving@fb.com>,
<stable@vger.kernel.org>, Joerg Roedel <jroedel@suse.de>,
Thomas Gleixner <tglx@linutronix.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
Andy Lutomirski <luto@kernel.org>,
Peter Zijlstra <peterz@infradead.org>
Subject: [PATCH] x86/mm/pti: in pti_clone_pgtable() don't increase addr by PUD_SIZE
Date: Tue, 20 Aug 2019 00:51:28 -0700 [thread overview]
Message-ID: <20190820075128.2912224-1-songliubraving@fb.com> (raw)
pti_clone_pgtable() increases addr by PUD_SIZE for pud_none(*pud) case.
This is not accurate because addr may not be PUD_SIZE aligned.
In our x86_64 kernel, pti_clone_pgtable() fails to clone 7 PMDs because
of this issuse, including PMD for the irq entry table. For a memcache
like workload, this introduces about 4.5x more iTLB-load and about 2.5x
more iTLB-load-misses on a Skylake CPU.
This patch fixes this issue by adding PMD_SIZE to addr for pud_none()
case.
Cc: stable@vger.kernel.org # v4.19+
Fixes: 16a3fe634f6a ("x86/mm/pti: Clone kernel-image on PTE level for 32 bit")
Signed-off-by: Song Liu <songliubraving@fb.com>
Cc: Joerg Roedel <jroedel@suse.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
---
arch/x86/mm/pti.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/mm/pti.c b/arch/x86/mm/pti.c
index b196524759ec..5a67c3015f59 100644
--- a/arch/x86/mm/pti.c
+++ b/arch/x86/mm/pti.c
@@ -330,7 +330,7 @@ pti_clone_pgtable(unsigned long start, unsigned long end,
pud = pud_offset(p4d, addr);
if (pud_none(*pud)) {
- addr += PUD_SIZE;
+ addr += PMD_SIZE;
continue;
}
--
2.17.1
next reply other threads:[~2019-08-20 7:51 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-20 7:51 Song Liu [this message]
2019-08-20 9:12 ` [PATCH] x86/mm/pti: in pti_clone_pgtable() don't increase addr by PUD_SIZE Thomas Gleixner
2019-08-20 13:17 ` Song Liu
2019-08-20 10:00 ` Peter Zijlstra
2019-08-20 11:16 ` Thomas Gleixner
2019-08-20 13:21 ` Song Liu
2019-08-20 13:39 ` Thomas Gleixner
2019-08-20 13:55 ` Rik van Riel
2019-08-20 14:00 ` Song Liu
2019-08-20 16:56 ` [PATCH v2] " Rik van Riel
2019-08-20 13:21 ` [PATCH] " Rik van Riel
2019-08-20 13:19 ` Song Liu
2019-08-20 13:57 ` Dave Hansen
2019-08-20 14:14 ` Song Liu
2019-08-20 14:18 ` Dave Hansen
2019-08-20 16:05 ` Song Liu
2019-08-20 16:38 ` Song Liu
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