From: Michel Lespinasse <michel@lespinasse.org>
To: Linux-MM <linux-mm@kvack.org>
Cc: Laurent Dufour <ldufour@linux.ibm.com>,
Peter Zijlstra <peterz@infradead.org>,
Michal Hocko <mhocko@suse.com>,
Matthew Wilcox <willy@infradead.org>,
Rik van Riel <riel@surriel.com>,
Paul McKenney <paulmck@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Suren Baghdasaryan <surenb@google.com>,
Joel Fernandes <joelaf@google.com>,
Rom Lemarchand <romlem@google.com>,
Linux-Kernel <linux-kernel@vger.kernel.org>,
Michel Lespinasse <michel@lespinasse.org>
Subject: [RFC PATCH 30/37] mm: enable speculative fault handling for supported file types.
Date: Tue, 6 Apr 2021 18:44:55 -0700 [thread overview]
Message-ID: <20210407014502.24091-31-michel@lespinasse.org> (raw)
In-Reply-To: <20210407014502.24091-1-michel@lespinasse.org>
Introduce vma_can_speculate(), which allows speculative handling for
VMAs mapping supported file types.
From do_handle_mm_fault(), speculative handling will follow through
__handle_mm_fault(), handle_pte_fault() and do_fault().
At this point, we expect speculative faults to continue through one of:
- do_read_fault(), fully implemented;
- do_cow_fault(), which might abort if missing anon vmas,
- do_shared_fault(), not implemented yet
(would require ->page_mkwrite() changes).
vma_can_speculate() provides an early abort for the do_shared_fault() case,
limiting the time spent on trying that unimplemented case.
Signed-off-by: Michel Lespinasse <michel@lespinasse.org>
---
arch/x86/mm/fault.c | 3 ++-
include/linux/mm.h | 14 ++++++++++++++
mm/memory.c | 17 ++++++++++++-----
3 files changed, 28 insertions(+), 6 deletions(-)
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index fbf265f56a06..48b86911a6df 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -1324,7 +1324,8 @@ void do_user_addr_fault(struct pt_regs *regs,
goto spf_abort;
rcu_read_lock();
vma = find_vma(mm, address);
- if (!vma || vma->vm_start > address || !vma_is_anonymous(vma)) {
+ if (!vma || vma->vm_start > address ||
+ !vma_can_speculate(vma, flags)) {
rcu_read_unlock();
goto spf_abort;
}
diff --git a/include/linux/mm.h b/include/linux/mm.h
index b4c0c10e434e..edb809e9036b 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -700,6 +700,20 @@ static inline bool vma_is_accessible(struct vm_area_struct *vma)
return vma->vm_flags & VM_ACCESS_FLAGS;
}
+static inline bool vma_can_speculate(struct vm_area_struct *vma,
+ unsigned int flags)
+{
+ if (vma_is_anonymous(vma))
+ return true;
+ if (!vma->vm_ops->speculative)
+ return false;
+ if (!(flags & FAULT_FLAG_WRITE))
+ return true;
+ if (!(vma->vm_flags & VM_SHARED))
+ return true;
+ return false;
+}
+
#ifdef CONFIG_SHMEM
/*
* The vma_is_shmem is not inline because it is used only by slow
diff --git a/mm/memory.c b/mm/memory.c
index a20e13d84145..074945faf1ab 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -4090,8 +4090,12 @@ static vm_fault_t do_cow_fault(struct vm_fault *vmf)
struct vm_area_struct *vma = vmf->vma;
vm_fault_t ret;
- if (unlikely(anon_vma_prepare(vma)))
- return VM_FAULT_OOM;
+ if (unlikely(!vma->anon_vma)) {
+ if (vmf->flags & FAULT_FLAG_SPECULATIVE)
+ return VM_FAULT_RETRY;
+ if (__anon_vma_prepare(vma))
+ return VM_FAULT_OOM;
+ }
vmf->cow_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vmf->address);
if (!vmf->cow_page)
@@ -4128,6 +4132,8 @@ static vm_fault_t do_shared_fault(struct vm_fault *vmf)
struct vm_area_struct *vma = vmf->vma;
vm_fault_t ret, tmp;
+ VM_BUG_ON(vmf->flags & FAULT_FLAG_SPECULATIVE);
+
ret = __do_fault(vmf);
if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
return ret;
@@ -4172,12 +4178,12 @@ static vm_fault_t do_fault(struct vm_fault *vmf)
struct mm_struct *vm_mm = vma->vm_mm;
vm_fault_t ret;
- VM_BUG_ON(vmf->flags & FAULT_FLAG_SPECULATIVE);
-
/*
* The VMA was not fully populated on mmap() or missing VM_DONTEXPAND
*/
if (!vma->vm_ops->fault) {
+ VM_BUG_ON(vmf->flags & FAULT_FLAG_SPECULATIVE);
+
/*
* If we find a migration pmd entry or a none pmd entry, which
* should never happen, return SIGBUS
@@ -4739,7 +4745,8 @@ vm_fault_t do_handle_mm_fault(struct vm_area_struct *vma,
{
vm_fault_t ret;
- VM_BUG_ON((flags & FAULT_FLAG_SPECULATIVE) && !vma_is_anonymous(vma));
+ VM_BUG_ON((flags & FAULT_FLAG_SPECULATIVE) &&
+ !vma_can_speculate(vma, flags));
__set_current_state(TASK_RUNNING);
--
2.20.1
next prev parent reply other threads:[~2021-04-07 1:52 UTC|newest]
Thread overview: 85+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-07 1:44 [RFC PATCH 00/37] Speculative page faults Michel Lespinasse
2021-04-07 1:44 ` [RFC PATCH 01/37] mmap locking API: mmap_lock_is_contended returns a bool Michel Lespinasse
2021-04-07 1:44 ` [RFC PATCH 02/37] mmap locking API: name the return values Michel Lespinasse
2021-04-07 1:44 ` [RFC PATCH 03/37] do_anonymous_page: use update_mmu_tlb() Michel Lespinasse
2021-04-07 2:06 ` Michel Lespinasse
2021-04-07 1:44 ` [RFC PATCH 04/37] do_anonymous_page: reduce code duplication Michel Lespinasse
2021-04-07 1:44 ` [RFC PATCH 05/37] mm: introduce CONFIG_SPECULATIVE_PAGE_FAULT Michel Lespinasse
2021-04-07 1:44 ` [RFC PATCH 06/37] x86/mm: define ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT Michel Lespinasse
2021-04-07 1:44 ` [RFC PATCH 07/37] mm: add FAULT_FLAG_SPECULATIVE flag Michel Lespinasse
2021-04-07 1:44 ` [RFC PATCH 08/37] mm: add do_handle_mm_fault() Michel Lespinasse
2021-04-07 1:44 ` [RFC PATCH 09/37] mm: add per-mm mmap sequence counter for speculative page fault handling Michel Lespinasse
2021-04-07 14:47 ` Peter Zijlstra
2021-04-07 20:50 ` Michel Lespinasse
2021-04-07 1:44 ` [RFC PATCH 10/37] mm: rcu safe vma freeing Michel Lespinasse
2021-04-07 1:44 ` [RFC PATCH 11/37] x86/mm: attempt speculative mm faults first Michel Lespinasse
2021-04-07 14:48 ` Peter Zijlstra
2021-04-07 15:35 ` Matthew Wilcox
2021-04-07 20:32 ` Michel Lespinasse
2021-04-07 20:14 ` Michel Lespinasse
2021-04-07 20:18 ` Michel Lespinasse
2021-04-07 1:44 ` [RFC PATCH 12/37] mm: refactor __handle_mm_fault() / handle_pte_fault() Michel Lespinasse
2021-04-07 1:44 ` [RFC PATCH 13/37] mm: implement speculative handling in __handle_mm_fault() Michel Lespinasse
2021-04-07 15:36 ` Andy Lutomirski
2021-04-28 14:58 ` Michel Lespinasse
2021-04-28 15:13 ` Andy Lutomirski
2021-04-28 16:11 ` Paul E. McKenney
2021-04-29 0:02 ` Michel Lespinasse
2021-04-29 0:05 ` Andy Lutomirski
2021-04-29 16:12 ` Matthew Wilcox
2021-04-29 18:04 ` Andy Lutomirski
2021-04-29 19:14 ` Michel Lespinasse
2021-04-29 19:34 ` Matthew Wilcox
2021-04-29 23:56 ` Michel Lespinasse
2021-04-29 15:52 ` Paul E. McKenney
2021-04-29 18:34 ` Paul E. McKenney
2021-04-29 18:49 ` Matthew Wilcox
2021-05-03 3:14 ` Paul E. McKenney
2021-04-29 21:17 ` Michel Lespinasse
2021-05-03 3:40 ` Paul E. McKenney
2021-05-03 4:34 ` Michel Lespinasse
2021-05-03 16:32 ` Paul E. McKenney
2021-04-07 1:44 ` [RFC PATCH 14/37] mm: add pte_map_lock() and pte_spinlock() Michel Lespinasse
2021-04-07 1:44 ` [RFC PATCH 15/37] mm: implement speculative handling in do_anonymous_page() Michel Lespinasse
2021-04-07 1:44 ` [RFC PATCH 16/37] mm: enable speculative fault handling through do_anonymous_page() Michel Lespinasse
2021-04-07 1:44 ` [RFC PATCH 17/37] mm: implement speculative handling in do_numa_page() Michel Lespinasse
2021-04-07 1:44 ` [RFC PATCH 18/37] mm: enable speculative fault " Michel Lespinasse
2021-04-07 1:44 ` [RFC PATCH 19/37] mm: implement speculative handling in wp_page_copy() Michel Lespinasse
2021-04-07 1:44 ` [RFC PATCH 20/37] mm: implement and enable speculative fault handling in handle_pte_fault() Michel Lespinasse
2021-04-07 1:44 ` [RFC PATCH 21/37] mm: implement speculative handling in do_swap_page() Michel Lespinasse
2021-04-07 1:44 ` [RFC PATCH 22/37] mm: enable speculative fault handling through do_swap_page() Michel Lespinasse
2021-04-07 1:44 ` [RFC PATCH 23/37] mm: rcu safe vma->vm_file freeing Michel Lespinasse
2021-04-08 5:12 ` [mm] 87b1c39af4: nvml.blk_rw_mt_TEST0_check_pmem_debug.fail kernel test robot
2021-04-07 1:44 ` [RFC PATCH 24/37] mm: implement speculative handling in __do_fault() Michel Lespinasse
2021-04-07 2:35 ` Matthew Wilcox
2021-04-07 2:53 ` Michel Lespinasse
2021-04-07 3:01 ` Matthew Wilcox
2021-04-07 14:40 ` Peter Zijlstra
2021-04-07 21:20 ` Michel Lespinasse
2021-04-07 21:27 ` Matthew Wilcox
2021-04-08 7:00 ` Peter Zijlstra
2021-04-08 7:13 ` Matthew Wilcox
2021-04-08 8:18 ` Peter Zijlstra
2021-04-08 8:37 ` Michel Lespinasse
2021-04-08 11:28 ` Matthew Wilcox
2021-04-07 1:44 ` [RFC PATCH 25/37] mm: implement speculative handling in filemap_fault() Michel Lespinasse
2021-04-07 1:44 ` [RFC PATCH 26/37] mm: implement speculative fault handling in finish_fault() Michel Lespinasse
2021-04-07 1:44 ` [RFC PATCH 27/37] mm: implement speculative handling in do_fault_around() Michel Lespinasse
2021-04-07 2:37 ` Matthew Wilcox
2021-04-07 1:44 ` [RFC PATCH 28/37] mm: implement speculative handling in filemap_map_pages() Michel Lespinasse
2021-04-07 1:44 ` [RFC PATCH 29/37] fs: list file types that support speculative faults Michel Lespinasse
2021-04-07 2:39 ` Matthew Wilcox
2021-04-07 1:44 ` Michel Lespinasse [this message]
2021-04-07 1:44 ` [RFC PATCH 31/37] ext4: implement speculative fault handling Michel Lespinasse
2021-04-07 1:44 ` [RFC PATCH 32/37] f2fs: " Michel Lespinasse
2021-04-07 1:44 ` [RFC PATCH 33/37] mm: enable speculative fault handling only for multithreaded user space Michel Lespinasse
2021-04-07 2:48 ` Matthew Wilcox
2021-04-07 1:44 ` [RFC PATCH 34/37] mm: rcu safe vma freeing " Michel Lespinasse
2021-04-07 2:50 ` Matthew Wilcox
2021-04-08 7:53 ` Michel Lespinasse
2021-04-07 1:45 ` [RFC PATCH 35/37] mm: spf statistics Michel Lespinasse
2021-04-07 1:45 ` [RFC PATCH 36/37] arm64/mm: define ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT Michel Lespinasse
2021-04-07 1:45 ` [RFC PATCH 37/37] arm64/mm: attempt speculative mm faults first Michel Lespinasse
2021-04-21 1:44 ` [RFC PATCH 00/37] Speculative page faults Chinwen Chang
2021-06-28 22:14 ` Axel Rasmussen
2021-07-21 11:33 ` vjitta
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