From: Laurent Dufour <ldufour@linux.ibm.com>
To: akpm@linux-foundation.org, mhocko@kernel.org,
peterz@infradead.org, kirill@shutemov.name, ak@linux.intel.com,
dave@stgolabs.net, jack@suse.cz,
Matthew Wilcox <willy@infradead.org>,
aneesh.kumar@linux.ibm.com, 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>,
sergey.senozhatsky.work@gmail.com,
Andrea Arcangeli <aarcange@redhat.com>,
Alexei Starovoitov <alexei.starovoitov@gmail.com>,
kemi.wang@intel.com, Daniel Jordan <daniel.m.jordan@oracle.com>,
David Rientjes <rientjes@google.com>,
Jerome Glisse <jglisse@redhat.com>,
Ganesh Mahendran <opensource.ganesh@gmail.com>,
Minchan Kim <minchan@kernel.org>,
Punit Agrawal <punitagrawal@gmail.com>,
vinayak menon <vinayakm.list@gmail.com>,
Yang Shi <yang.shi@linux.alibaba.com>,
zhong jiang <zhongjiang@huawei.com>,
Haiyan Song <haiyanx.song@intel.com>,
Balbir Singh <bsingharora@gmail.com>,
sj38.park@gmail.com, Michel Lespinasse <walken@google.com>,
Mike Rapoport <rppt@linux.ibm.com>
Cc: linuxppc-dev@lists.ozlabs.org, x86@kernel.org,
linux-kernel@vger.kernel.org, npiggin@gmail.com,
linux-mm@kvack.org, paulmck@linux.vnet.ibm.com,
Tim Chen <tim.c.chen@linux.intel.com>,
haren@linux.vnet.ibm.com
Subject: [PATCH v12 07/31] mm: make pte_unmap_same compatible with SPF
Date: Tue, 16 Apr 2019 15:44:58 +0200 [thread overview]
Message-ID: <20190416134522.17540-8-ldufour@linux.ibm.com> (raw)
In-Reply-To: <20190416134522.17540-1-ldufour@linux.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.
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Laurent Dufour <ldufour@linux.ibm.com>
---
include/linux/mm_types.h | 6 +++++-
mm/memory.c | 37 +++++++++++++++++++++++++++----------
2 files changed, 32 insertions(+), 11 deletions(-)
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 8ec38b11b361..fd7d38ee2e33 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -652,6 +652,8 @@ typedef __bitwise unsigned int vm_fault_t;
* @VM_FAULT_NEEDDSYNC: ->fault did not modify page tables and needs
* fsync() to complete (for synchronous page faults
* in DAX)
+ * @VM_FAULT_PTNOTSAME Page table entries have changed during a
+ * speculative page fault handling.
* @VM_FAULT_HINDEX_MASK: mask HINDEX value
*
*/
@@ -669,6 +671,7 @@ enum vm_fault_reason {
VM_FAULT_FALLBACK = (__force vm_fault_t)0x000800,
VM_FAULT_DONE_COW = (__force vm_fault_t)0x001000,
VM_FAULT_NEEDDSYNC = (__force vm_fault_t)0x002000,
+ VM_FAULT_PTNOTSAME = (__force vm_fault_t)0x004000,
VM_FAULT_HINDEX_MASK = (__force vm_fault_t)0x0f0000,
};
@@ -693,7 +696,8 @@ enum vm_fault_reason {
{ VM_FAULT_RETRY, "RETRY" }, \
{ VM_FAULT_FALLBACK, "FALLBACK" }, \
{ VM_FAULT_DONE_COW, "DONE_COW" }, \
- { VM_FAULT_NEEDDSYNC, "NEEDDSYNC" }
+ { VM_FAULT_NEEDDSYNC, "NEEDDSYNC" }, \
+ { VM_FAULT_PTNOTSAME, "PTNOTSAME" }
struct vm_special_mapping {
const char *name; /* The name, e.g. "[vdso]". */
diff --git a/mm/memory.c b/mm/memory.c
index 221ccdf34991..d5bebca47d98 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2094,21 +2094,29 @@ static inline 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 vm_fault_t 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)
@@ -2714,8 +2722,17 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
int exclusive = 0;
vm_fault_t ret = 0;
- if (!pte_unmap_same(vma->vm_mm, vmf->pmd, vmf->pte, vmf->orig_pte))
+ ret = pte_unmap_same(vmf);
+ if (ret) {
+ /*
+ * If pte != orig_pte, this means another thread did the
+ * swap operation in our back.
+ * So nothing else to do.
+ */
+ if (ret == VM_FAULT_PTNOTSAME)
+ ret = 0;
goto out;
+ }
entry = pte_to_swp_entry(vmf->orig_pte);
if (unlikely(non_swap_entry(entry))) {
--
2.21.0
next prev parent reply other threads:[~2019-04-16 21:16 UTC|newest]
Thread overview: 98+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-16 13:44 [PATCH v12 00/31] Speculative page faults Laurent Dufour
2019-04-16 13:44 ` [PATCH v12 01/31] mm: introduce CONFIG_SPECULATIVE_PAGE_FAULT Laurent Dufour
2019-04-18 21:47 ` Jerome Glisse
2019-04-23 15:21 ` Laurent Dufour
2019-04-16 13:44 ` [PATCH v12 02/31] x86/mm: define ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT Laurent Dufour
2019-04-18 21:48 ` Jerome Glisse
2019-04-16 13:44 ` [PATCH v12 03/31] powerpc/mm: set ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT Laurent Dufour
2019-04-18 21:49 ` Jerome Glisse
2019-04-16 13:44 ` [PATCH v12 04/31] arm64/mm: define ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT Laurent Dufour
2019-04-16 14:27 ` Mark Rutland
2019-04-16 14:31 ` Laurent Dufour
2019-04-16 14:41 ` Mark Rutland
2019-04-18 21:51 ` Jerome Glisse
2019-04-23 15:36 ` Laurent Dufour
2019-04-23 16:19 ` Mark Rutland
2019-04-24 10:34 ` Laurent Dufour
2019-04-16 13:44 ` [PATCH v12 05/31] mm: prepare for FAULT_FLAG_SPECULATIVE Laurent Dufour
2019-04-18 22:04 ` Jerome Glisse
2019-04-23 15:45 ` Laurent Dufour
2019-04-16 13:44 ` [PATCH v12 06/31] mm: introduce pte_spinlock " Laurent Dufour
2019-04-18 22:05 ` Jerome Glisse
2019-04-16 13:44 ` Laurent Dufour [this message]
2019-04-18 22:10 ` [PATCH v12 07/31] mm: make pte_unmap_same compatible with SPF Jerome Glisse
2019-04-23 15:43 ` Matthew Wilcox
2019-04-23 15:47 ` Laurent Dufour
2019-04-16 13:44 ` [PATCH v12 08/31] mm: introduce INIT_VMA() Laurent Dufour
2019-04-18 22:22 ` Jerome Glisse
2019-04-16 13:45 ` [PATCH v12 09/31] mm: VMA sequence count Laurent Dufour
2019-04-18 22:48 ` Jerome Glisse
2019-04-19 15:45 ` Laurent Dufour
2019-04-22 15:51 ` Jerome Glisse
2019-04-16 13:45 ` [PATCH v12 10/31] mm: protect VMA modifications using " Laurent Dufour
2019-04-22 19:43 ` Jerome Glisse
2019-04-16 13:45 ` [PATCH v12 11/31] mm: protect mremap() against SPF hanlder Laurent Dufour
2019-04-22 19:51 ` Jerome Glisse
2019-04-23 15:51 ` Laurent Dufour
2019-04-16 13:45 ` [PATCH v12 12/31] mm: protect SPF handler against anon_vma changes Laurent Dufour
2019-04-22 19:53 ` Jerome Glisse
2019-04-16 13:45 ` [PATCH v12 13/31] mm: cache some VMA fields in the vm_fault structure Laurent Dufour
2019-04-22 20:06 ` Jerome Glisse
2019-04-16 13:45 ` [PATCH v12 14/31] mm/migrate: Pass vm_fault pointer to migrate_misplaced_page() Laurent Dufour
2019-04-22 20:09 ` Jerome Glisse
2019-04-16 13:45 ` [PATCH v12 15/31] mm: introduce __lru_cache_add_active_or_unevictable Laurent Dufour
2019-04-22 20:11 ` Jerome Glisse
2019-04-16 13:45 ` [PATCH v12 16/31] mm: introduce __vm_normal_page() Laurent Dufour
2019-04-22 20:15 ` Jerome Glisse
2019-04-16 13:45 ` [PATCH v12 17/31] mm: introduce __page_add_new_anon_rmap() Laurent Dufour
2019-04-22 20:18 ` Jerome Glisse
2019-04-16 13:45 ` [PATCH v12 18/31] mm: protect against PTE changes done by dup_mmap() Laurent Dufour
2019-04-22 20:32 ` Jerome Glisse
2019-04-24 10:33 ` Laurent Dufour
2019-04-16 13:45 ` [PATCH v12 19/31] mm: protect the RB tree with a sequence lock Laurent Dufour
2019-04-22 20:33 ` Jerome Glisse
2019-04-16 13:45 ` [PATCH v12 20/31] mm: introduce vma reference counter Laurent Dufour
2019-04-22 20:36 ` Jerome Glisse
2019-04-24 14:26 ` Laurent Dufour
2019-04-16 13:45 ` [PATCH v12 21/31] mm: Introduce find_vma_rcu() Laurent Dufour
2019-04-22 20:57 ` Jerome Glisse
2019-04-24 14:39 ` Laurent Dufour
2019-04-23 9:27 ` Peter Zijlstra
2019-04-23 18:13 ` Davidlohr Bueso
2019-04-24 7:57 ` Laurent Dufour
2019-04-16 13:45 ` [PATCH v12 22/31] mm: provide speculative fault infrastructure Laurent Dufour
2019-04-22 21:26 ` Jerome Glisse
2019-04-24 14:56 ` Laurent Dufour
2019-04-24 15:13 ` Jerome Glisse
2019-04-16 13:45 ` [PATCH v12 23/31] mm: don't do swap readahead during speculative page fault Laurent Dufour
2019-04-22 21:36 ` Jerome Glisse
2019-04-24 14:57 ` Laurent Dufour
2019-04-16 13:45 ` [PATCH v12 24/31] mm: adding speculative page fault failure trace events Laurent Dufour
2019-04-16 13:45 ` [PATCH v12 25/31] perf: add a speculative page fault sw event Laurent Dufour
2019-04-16 13:45 ` [PATCH v12 26/31] perf tools: add support for the SPF perf event Laurent Dufour
2019-04-16 13:45 ` [PATCH v12 27/31] mm: add speculative page fault vmstats Laurent Dufour
2019-04-16 13:45 ` [PATCH v12 28/31] x86/mm: add speculative pagefault handling Laurent Dufour
2019-04-16 13:45 ` [PATCH v12 29/31] powerpc/mm: add speculative page fault Laurent Dufour
2019-04-16 13:45 ` [PATCH v12 30/31] arm64/mm: " Laurent Dufour
2019-04-16 13:45 ` [PATCH v12 31/31] mm: Add a speculative page fault switch in sysctl Laurent Dufour
2019-04-22 21:29 ` [PATCH v12 00/31] Speculative page faults Michel Lespinasse
2019-04-23 9:38 ` Peter Zijlstra
2019-04-24 7:33 ` Laurent Dufour
2019-04-27 1:53 ` Michel Lespinasse
2019-04-23 10:47 ` Michal Hocko
2019-04-23 12:41 ` Matthew Wilcox
2019-04-23 12:48 ` Peter Zijlstra
2019-04-23 13:42 ` Michal Hocko
2019-04-24 18:01 ` Laurent Dufour
2019-04-27 6:00 ` Michel Lespinasse
2019-04-23 11:35 ` Anshuman Khandual
2019-06-06 6:51 ` Haiyan Song
2019-06-14 8:37 ` Laurent Dufour
2019-06-14 8:44 ` Laurent Dufour
2019-06-20 8:19 ` Haiyan Song
2020-07-06 9:25 ` Chinwen Chang
2020-07-06 12:27 ` Laurent Dufour
2020-07-07 5:31 ` Chinwen Chang
2020-12-14 2:03 ` Joel Fernandes
2020-12-14 9:36 ` Laurent Dufour
2020-12-14 18:10 ` Joel Fernandes
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