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 v9 06/24] mm: make pte_unmap_same compatible with SPF
Date: Tue, 13 Mar 2018 18:59:36 +0100 [thread overview]
Message-ID: <1520963994-28477-7-git-send-email-ldufour@linux.vnet.ibm.com> (raw)
In-Reply-To: <1520963994-28477-1-git-send-email-ldufour@linux.vnet.ibm.com>
pte_unmap_same() is making the assumption that the page table are still
around because the mmap_sem is held.
This is no more the case when running a speculative page fault and
additional check must be made to ensure that the final page table are still
there.
This is now done by calling pte_spinlock() to check for the VMA's
consistency while locking for the page tables.
This is requiring passing a vm_fault structure to pte_unmap_same() which is
containing all the needed parameters.
As pte_spinlock() may fail in the case of a speculative page fault, if the
VMA has been touched in our back, pte_unmap_same() should now return 3
cases :
1. pte are the same (0)
2. pte are different (VM_FAULT_PTNOTSAME)
3. a VMA's changes has been detected (VM_FAULT_RETRY)
The case 2 is handled by the introduction of a new VM_FAULT flag named
VM_FAULT_PTNOTSAME which is then trapped in cow_user_page().
If VM_FAULT_RETRY is returned, it is passed up to the callers to retry the
page fault while holding the mmap_sem.
Signed-off-by: Laurent Dufour <ldufour@linux.vnet.ibm.com>
---
include/linux/mm.h | 1 +
mm/memory.c | 29 +++++++++++++++++++----------
2 files changed, 20 insertions(+), 10 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 2f3e98edc94a..b6432a261e63 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1199,6 +1199,7 @@ static inline void clear_page_pfmemalloc(struct page *page)
#define VM_FAULT_NEEDDSYNC 0x2000 /* ->fault did not modify page tables
* and needs fsync() to complete (for
* synchronous page faults in DAX) */
+#define VM_FAULT_PTNOTSAME 0x4000 /* Page table entries have changed */
#define VM_FAULT_ERROR (VM_FAULT_OOM | VM_FAULT_SIGBUS | VM_FAULT_SIGSEGV | \
VM_FAULT_HWPOISON | VM_FAULT_HWPOISON_LARGE | \
diff --git a/mm/memory.c b/mm/memory.c
index 21b1212a0892..4bc7b0bdcb40 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2309,21 +2309,29 @@ static bool pte_map_lock(struct vm_fault *vmf)
* parts, do_swap_page must check under lock before unmapping the pte and
* proceeding (but do_wp_page is only called after already making such a check;
* and do_anonymous_page can safely check later on).
+ *
+ * pte_unmap_same() returns:
+ * 0 if the PTE are the same
+ * VM_FAULT_PTNOTSAME if the PTE are different
+ * VM_FAULT_RETRY if the VMA has changed in our back during
+ * a speculative page fault handling.
*/
-static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
- pte_t *page_table, pte_t orig_pte)
+static inline int pte_unmap_same(struct vm_fault *vmf)
{
- int same = 1;
+ int ret = 0;
+
#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
if (sizeof(pte_t) > sizeof(unsigned long)) {
- spinlock_t *ptl = pte_lockptr(mm, pmd);
- spin_lock(ptl);
- same = pte_same(*page_table, orig_pte);
- spin_unlock(ptl);
+ if (pte_spinlock(vmf)) {
+ if (!pte_same(*vmf->pte, vmf->orig_pte))
+ ret = VM_FAULT_PTNOTSAME;
+ spin_unlock(vmf->ptl);
+ } else
+ ret = VM_FAULT_RETRY;
}
#endif
- pte_unmap(page_table);
- return same;
+ pte_unmap(vmf->pte);
+ return ret;
}
static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
@@ -2913,7 +2921,8 @@ int do_swap_page(struct vm_fault *vmf)
int exclusive = 0;
int ret = 0;
- if (!pte_unmap_same(vma->vm_mm, vmf->pmd, vmf->pte, vmf->orig_pte))
+ ret = pte_unmap_same(vmf);
+ if (ret)
goto out;
entry = pte_to_swp_entry(vmf->orig_pte);
--
2.7.4
next prev parent reply other threads:[~2018-03-13 18:00 UTC|newest]
Thread overview: 98+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-13 17:59 [PATCH v9 00/24] Speculative page faults Laurent Dufour
2018-03-13 17:59 ` [PATCH v9 01/24] mm: Introduce CONFIG_SPECULATIVE_PAGE_FAULT Laurent Dufour
2018-03-25 21:50 ` David Rientjes
2018-03-28 7:49 ` Laurent Dufour
2018-03-28 10:16 ` David Rientjes
2018-03-28 11:15 ` Laurent Dufour
2018-03-28 21:18 ` David Rientjes
2018-03-13 17:59 ` [PATCH v9 02/24] x86/mm: Define CONFIG_SPECULATIVE_PAGE_FAULT Laurent Dufour
2018-03-13 17:59 ` [PATCH v9 03/24] powerpc/mm: " Laurent Dufour
2018-03-13 17:59 ` [PATCH v9 05/24] mm: Introduce pte_spinlock for FAULT_FLAG_SPECULATIVE Laurent Dufour
2018-03-25 21:50 ` David Rientjes
2018-03-28 8:15 ` Laurent Dufour
2018-03-13 17:59 ` Laurent Dufour [this message]
2018-03-27 21:18 ` [PATCH v9 06/24] mm: make pte_unmap_same compatible with SPF David Rientjes
2018-03-28 8:27 ` Laurent Dufour
2018-03-28 10:20 ` David Rientjes
2018-03-28 10:43 ` Laurent Dufour
2018-04-03 19:10 ` Jerome Glisse
2018-04-03 20:40 ` David Rientjes
2018-04-03 21:04 ` Jerome Glisse
2018-04-04 9:53 ` Laurent Dufour
2018-03-13 17:59 ` [PATCH v9 08/24] mm: Protect VMA modifications using VMA sequence count Laurent Dufour
2018-03-27 21:45 ` David Rientjes
2018-03-28 16:57 ` Laurent Dufour
2018-03-27 21:57 ` David Rientjes
2018-03-28 17:10 ` Laurent Dufour
2018-03-13 17:59 ` [PATCH v9 09/24] mm: protect mremap() against SPF hanlder Laurent Dufour
2018-03-27 22:12 ` David Rientjes
2018-03-28 18:11 ` Laurent Dufour
2018-03-28 21:21 ` David Rientjes
2018-04-04 8:24 ` Laurent Dufour
2018-03-13 17:59 ` [PATCH v9 10/24] mm: Protect SPF handler against anon_vma changes Laurent Dufour
2018-03-13 17:59 ` [PATCH v9 11/24] mm: Cache some VMA fields in the vm_fault structure Laurent Dufour
2018-04-02 22:24 ` David Rientjes
2018-04-04 15:48 ` Laurent Dufour
2018-03-13 17:59 ` [PATCH v9 12/24] mm/migrate: Pass vm_fault pointer to migrate_misplaced_page() Laurent Dufour
2018-04-02 23:00 ` David Rientjes
2018-03-13 17:59 ` [PATCH v9 13/24] mm: Introduce __lru_cache_add_active_or_unevictable Laurent Dufour
2018-04-02 23:11 ` David Rientjes
2018-03-13 17:59 ` [PATCH v9 14/24] mm: Introduce __maybe_mkwrite() Laurent Dufour
2018-04-02 23:12 ` David Rientjes
2018-04-04 15:56 ` Laurent Dufour
2018-03-13 17:59 ` [PATCH v9 15/24] mm: Introduce __vm_normal_page() Laurent Dufour
2018-04-02 23:18 ` David Rientjes
2018-04-04 16:04 ` Laurent Dufour
2018-04-03 19:39 ` Jerome Glisse
2018-04-03 20:45 ` David Rientjes
2018-04-04 16:26 ` Laurent Dufour
2018-04-04 21:59 ` Jerome Glisse
2018-04-05 12:53 ` Laurent Dufour
2018-03-13 17:59 ` [PATCH v9 16/24] mm: Introduce __page_add_new_anon_rmap() Laurent Dufour
2018-04-02 23:57 ` David Rientjes
2018-04-10 16:30 ` Laurent Dufour
2018-03-13 17:59 ` [PATCH v9 17/24] mm: Protect mm_rb tree with a rwlock Laurent Dufour
2018-03-14 8:48 ` Peter Zijlstra
2018-03-14 16:25 ` Laurent Dufour
2018-03-16 10:23 ` [mm] b33ddf50eb: INFO:trying_to_register_non-static_key kernel test robot
2018-03-16 16:38 ` Laurent Dufour
2018-04-03 0:11 ` [PATCH v9 17/24] mm: Protect mm_rb tree with a rwlock David Rientjes
2018-04-06 14:23 ` Laurent Dufour
2018-04-10 16:20 ` Laurent Dufour
2018-03-13 17:59 ` [PATCH v9 18/24] mm: Provide speculative fault infrastructure Laurent Dufour
2018-03-13 17:59 ` [PATCH v9 19/24] mm: Adding speculative page fault failure trace events Laurent Dufour
2018-03-13 17:59 ` [PATCH v9 20/24] perf: Add a speculative page fault sw event Laurent Dufour
2018-03-26 21:43 ` David Rientjes
2018-03-13 17:59 ` [PATCH v9 21/24] perf tools: Add support for the SPF perf event Laurent Dufour
2018-03-26 21:44 ` David Rientjes
2018-03-27 3:49 ` Andi Kleen
2018-04-10 6:47 ` David Rientjes
2018-04-12 13:44 ` Laurent Dufour
2018-03-13 17:59 ` [PATCH v9 22/24] mm: Speculative page fault handler return VMA Laurent Dufour
2018-03-13 17:59 ` [PATCH v9 23/24] x86/mm: Add speculative pagefault handling Laurent Dufour
2018-03-26 21:41 ` David Rientjes
2018-03-13 17:59 ` [PATCH v9 24/24] powerpc/mm: Add speculative page fault Laurent Dufour
2018-03-26 21:39 ` David Rientjes
2018-03-14 13:11 ` [PATCH v9 00/24] Speculative page faults Michal Hocko
2018-03-14 13:33 ` Laurent Dufour
2018-04-13 13:34 ` Laurent Dufour
2018-03-22 1:21 ` Ganesh Mahendran
2018-03-29 12:49 ` Laurent Dufour
[not found] ` <1520963994-28477-5-git-send-email-ldufour@linux.vnet.ibm.com>
2018-03-25 21:50 ` [PATCH v9 04/24] mm: Prepare for FAULT_FLAG_SPECULATIVE David Rientjes
2018-03-28 10:27 ` Laurent Dufour
2018-04-03 21:57 ` David Rientjes
2018-04-04 9:23 ` Laurent Dufour
[not found] ` <1520963994-28477-8-git-send-email-ldufour@linux.vnet.ibm.com>
2018-03-17 7:51 ` [mm] b1f0502d04: INFO:trying_to_register_non-static_key kernel test robot
2018-03-21 12:21 ` Laurent Dufour
2018-03-25 22:10 ` David Rientjes
2018-03-28 13:30 ` Laurent Dufour
2018-04-04 0:48 ` David Rientjes
2018-04-04 1:03 ` David Rientjes
2018-04-04 10:28 ` Laurent Dufour
2018-04-04 10:19 ` Laurent Dufour
2018-04-04 21:53 ` David Rientjes
2018-04-05 16:55 ` Laurent Dufour
2018-03-27 21:30 ` [PATCH v9 07/24] mm: VMA sequence count David Rientjes
2018-03-28 17:58 ` Laurent Dufour
2018-04-03 20:37 ` [PATCH v9 00/24] Speculative page faults Jerome Glisse
2018-04-04 7:59 ` Laurent Dufour
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