From: Laurent Dufour <ldufour@linux.vnet.ibm.com>
To: paulmck@linux.vnet.ibm.com, peterz@infradead.org,
akpm@linux-foundation.org, kirill@shutemov.name,
ak@linux.intel.com, mhocko@kernel.org, dave@stgolabs.net,
jack@suse.cz, Matthew Wilcox <willy@infradead.org>,
benh@kernel.crashing.org, mpe@ellerman.id.au, paulus@samba.org,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
hpa@zytor.com, Will Deacon <will.deacon@arm.com>,
Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
Andrea Arcangeli <aarcange@redhat.com>,
Alexei Starovoitov <alexei.starovoitov@gmail.com>,
kemi.wang@intel.com, sergey.senozhatsky.work@gmail.com,
Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
haren@linux.vnet.ibm.com, khandual@linux.vnet.ibm.com,
npiggin@gmail.com, bsingharora@gmail.com,
Tim Chen <tim.c.chen@linux.intel.com>,
linuxppc-dev@lists.ozlabs.org, x86@kernel.org
Subject: [PATCH v7 23/24] x86/mm: Add speculative pagefault handling
Date: Tue, 6 Feb 2018 17:50:09 +0100 [thread overview]
Message-ID: <1517935810-31177-24-git-send-email-ldufour@linux.vnet.ibm.com> (raw)
In-Reply-To: <1517935810-31177-1-git-send-email-ldufour@linux.vnet.ibm.com>
From: Peter Zijlstra <peterz@infradead.org>
Try a speculative fault before acquiring mmap_sem, if it returns with
VM_FAULT_RETRY continue with the mmap_sem acquisition and do the
traditional fault.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
[Clearing of FAULT_FLAG_ALLOW_RETRY is now done in
handle_speculative_fault()]
[Retry with usual fault path in the case VM_ERROR is returned by
handle_speculative_fault(). This allows signal to be delivered]
[Don't build SPF call if !CONFIG_SPECULATIVE_PAGE_FAULT]
[Try speculative fault path only for multi threaded processes]
[Try to the VMA fetch during the speculative path in case of retry]
Signed-off-by: Laurent Dufour <ldufour@linux.vnet.ibm.com>
---
arch/x86/mm/fault.c | 38 +++++++++++++++++++++++++++++++++++++-
1 file changed, 37 insertions(+), 1 deletion(-)
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 800de815519c..d9f9236ccb9a 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -1239,6 +1239,9 @@ __do_page_fault(struct pt_regs *regs, unsigned long error_code,
unsigned long address)
{
struct vm_area_struct *vma;
+#ifdef CONFIG_SPECULATIVE_PAGE_FAULT
+ struct vm_area_struct *spf_vma = NULL;
+#endif
struct task_struct *tsk;
struct mm_struct *mm;
int fault, major = 0;
@@ -1336,6 +1339,27 @@ __do_page_fault(struct pt_regs *regs, unsigned long error_code,
if (error_code & X86_PF_INSTR)
flags |= FAULT_FLAG_INSTRUCTION;
+#ifdef CONFIG_SPECULATIVE_PAGE_FAULT
+ if ((error_code & X86_PF_USER) && (atomic_read(&mm->mm_users) > 1)) {
+ fault = handle_speculative_fault(mm, address, flags,
+ &spf_vma);
+
+ if (!(fault & VM_FAULT_RETRY)) {
+ if (!(fault & VM_FAULT_ERROR)) {
+ perf_sw_event(PERF_COUNT_SW_SPF, 1,
+ regs, address);
+ goto done;
+ }
+ /*
+ * In case of error we need the pkey value, but
+ * can't get it from the spf_vma as it is only returned
+ * when VM_FAULT_RETRY is returned. So we have to
+ * retry the page fault with the mmap_sem grabbed.
+ */
+ }
+ }
+#endif /* CONFIG_SPECULATIVE_PAGE_FAULT */
+
/*
* When running in the kernel we expect faults to occur only to
* addresses in user space. All other faults represent errors in
@@ -1369,7 +1393,16 @@ __do_page_fault(struct pt_regs *regs, unsigned long error_code,
might_sleep();
}
- vma = find_vma(mm, address);
+#ifdef CONFIG_SPECULATIVE_PAGE_FAULT
+ if (spf_vma) {
+ if (can_reuse_spf_vma(spf_vma, address))
+ vma = spf_vma;
+ else
+ vma = find_vma(mm, address);
+ spf_vma = NULL;
+ } else
+#endif
+ vma = find_vma(mm, address);
if (unlikely(!vma)) {
bad_area(regs, error_code, address);
return;
@@ -1455,6 +1488,9 @@ __do_page_fault(struct pt_regs *regs, unsigned long error_code,
return;
}
+#ifdef CONFIG_SPECULATIVE_PAGE_FAULT
+done:
+#endif
/*
* Major/minor page fault accounting. If any of the events
* returned VM_FAULT_MAJOR, we account it as a major fault.
--
2.7.4
next prev parent reply other threads:[~2018-02-06 16:51 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-06 16:49 [PATCH v7 00/24] Speculative page faults Laurent Dufour
2018-02-06 16:49 ` [PATCH v7 01/24] mm: Introduce CONFIG_SPECULATIVE_PAGE_FAULT Laurent Dufour
2018-02-06 16:49 ` [PATCH v7 02/24] x86/mm: Define CONFIG_SPECULATIVE_PAGE_FAULT Laurent Dufour
2018-02-06 16:49 ` [PATCH v7 03/24] powerpc/mm: " Laurent Dufour
2018-02-06 16:49 ` [PATCH v7 04/24] mm: Dont assume page-table invariance during faults Laurent Dufour
2018-02-06 20:28 ` Matthew Wilcox
2018-02-08 14:35 ` Laurent Dufour
2018-02-08 15:00 ` Matthew Wilcox
2018-02-08 17:14 ` Laurent Dufour
2018-02-06 16:49 ` [PATCH v7 05/24] mm: Prepare for FAULT_FLAG_SPECULATIVE Laurent Dufour
2018-02-06 16:49 ` [PATCH v7 06/24] mm: Introduce pte_spinlock " Laurent Dufour
2018-02-06 16:49 ` [PATCH v7 07/24] mm: VMA sequence count Laurent Dufour
2018-02-06 16:49 ` [PATCH v7 08/24] mm: Protect VMA modifications using " Laurent Dufour
2018-02-06 16:49 ` [PATCH v7 09/24] mm: protect mremap() against SPF hanlder Laurent Dufour
2018-02-06 16:49 ` [PATCH v7 10/24] mm: Protect SPF handler against anon_vma changes Laurent Dufour
2018-02-06 16:49 ` [PATCH v7 11/24] mm: Cache some VMA fields in the vm_fault structure Laurent Dufour
2018-02-06 16:49 ` [PATCH v7 12/24] mm/migrate: Pass vm_fault pointer to migrate_misplaced_page() Laurent Dufour
2018-02-06 16:49 ` [PATCH v7 13/24] mm: Introduce __lru_cache_add_active_or_unevictable Laurent Dufour
2018-02-06 16:50 ` [PATCH v7 14/24] mm: Introduce __maybe_mkwrite() Laurent Dufour
2018-02-06 16:50 ` [PATCH v7 15/24] mm: Introduce __vm_normal_page() Laurent Dufour
2018-02-06 16:50 ` [PATCH v7 16/24] mm: Introduce __page_add_new_anon_rmap() Laurent Dufour
2018-02-06 16:50 ` [PATCH v7 17/24] mm: Protect mm_rb tree with a rwlock Laurent Dufour
2018-02-06 16:50 ` [PATCH v7 18/24] mm: Provide speculative fault infrastructure Laurent Dufour
2018-02-06 16:50 ` [PATCH v7 19/24] mm: Adding speculative page fault failure trace events Laurent Dufour
2018-02-06 16:50 ` [PATCH v7 20/24] perf: Add a speculative page fault sw event Laurent Dufour
2018-02-06 16:50 ` [PATCH v7 21/24] perf tools: Add support for the SPF perf event Laurent Dufour
2018-02-06 16:50 ` [PATCH v7 22/24] mm: Speculative page fault handler return VMA Laurent Dufour
2018-02-06 16:50 ` Laurent Dufour [this message]
2018-02-06 16:50 ` [PATCH v7 24/24] powerpc/mm: Add speculative page fault Laurent Dufour
2018-02-08 20:53 ` [PATCH v7 00/24] Speculative page faults Andrew Morton
2018-02-13 7:56 ` Laurent Dufour
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