From: Liam Howlett <liam.howlett@oracle.com>
To: Michel Lespinasse <michel@lespinasse.org>
Cc: Linux-MM <linux-mm@kvack.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
"kernel-team@fb.com" <kernel-team@fb.com>,
Laurent Dufour <ldufour@linux.ibm.com>,
Jerome Glisse <jglisse@google.com>,
Peter Zijlstra <peterz@infradead.org>,
Michal Hocko <mhocko@suse.com>, Vlastimil Babka <vbabka@suse.cz>,
Davidlohr Bueso <dave@stgolabs.net>,
Matthew Wilcox <willy@infradead.org>,
Rik van Riel <riel@surriel.com>,
Paul McKenney <paulmck@kernel.org>,
Song Liu <songliubraving@fb.com>,
Suren Baghdasaryan <surenb@google.com>,
Minchan Kim <minchan@google.com>,
Joel Fernandes <joelaf@google.com>,
David Rientjes <rientjes@google.com>,
Axel Rasmussen <axelrasmussen@google.com>,
Andy Lutomirski <luto@kernel.org>
Subject: Re: [PATCH v2 13/35] x86/mm: attempt speculative mm faults first
Date: Tue, 1 Feb 2022 17:16:43 +0000 [thread overview]
Message-ID: <20220201171617.z5zgafitgolyv5np@revolver> (raw)
In-Reply-To: <20220128131006.67712-14-michel@lespinasse.org>
* Michel Lespinasse <michel@lespinasse.org> [220128 08:10]:
> Attempt speculative mm fault handling first, and fall back to the
> existing (non-speculative) code if that fails.
>
> The speculative handling closely mirrors the non-speculative logic.
> This includes some x86 specific bits such as the access_error() call.
> This is why we chose to implement the speculative handling in arch/x86
> rather than in common code.
>
> The vma is first looked up and copied, under protection of the rcu
> read lock. The mmap lock sequence count is used to verify the
> integrity of the copied vma, and passed to do_handle_mm_fault() to
> allow checking against races with mmap writers when finalizing the fault.
>
> Signed-off-by: Michel Lespinasse <michel@lespinasse.org>
> ---
> arch/x86/mm/fault.c | 44 +++++++++++++++++++++++++++++++++++
> include/linux/mm_types.h | 5 ++++
> include/linux/vm_event_item.h | 4 ++++
> mm/vmstat.c | 4 ++++
> 4 files changed, 57 insertions(+)
>
> diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
> index d0074c6ed31a..99b0a358154e 100644
> --- a/arch/x86/mm/fault.c
> +++ b/arch/x86/mm/fault.c
> @@ -1226,6 +1226,10 @@ void do_user_addr_fault(struct pt_regs *regs,
> struct mm_struct *mm;
> vm_fault_t fault;
> unsigned int flags = FAULT_FLAG_DEFAULT;
> +#ifdef CONFIG_SPECULATIVE_PAGE_FAULT
> + struct vm_area_struct pvma;
> + unsigned long seq;
> +#endif
>
> tsk = current;
> mm = tsk->mm;
> @@ -1323,6 +1327,43 @@ void do_user_addr_fault(struct pt_regs *regs,
> }
> #endif
>
> +#ifdef CONFIG_SPECULATIVE_PAGE_FAULT
> + count_vm_event(SPF_ATTEMPT);
> + seq = mmap_seq_read_start(mm);
> + if (seq & 1)
> + goto spf_abort;
> + rcu_read_lock();
> + vma = __find_vma(mm, address);
> + if (!vma || vma->vm_start > address) {
This fits the vma_lookup() pattern - although you will have to work
around the locking issue still. This is the same for the other
platforms too; they fit the pattern also.
> + rcu_read_unlock();
> + goto spf_abort;
> + }
> + pvma = *vma;
> + rcu_read_unlock();
> + if (!mmap_seq_read_check(mm, seq))
> + goto spf_abort;
> + vma = &pvma;
> + if (unlikely(access_error(error_code, vma)))
> + goto spf_abort;
> + fault = do_handle_mm_fault(vma, address,
> + flags | FAULT_FLAG_SPECULATIVE, seq, regs);
> +
> + if (!(fault & VM_FAULT_RETRY))
> + goto done;
> +
> + /* Quick path to respond to signals */
> + if (fault_signal_pending(fault, regs)) {
> + if (!user_mode(regs))
> + kernelmode_fixup_or_oops(regs, error_code, address,
> + SIGBUS, BUS_ADRERR,
> + ARCH_DEFAULT_PKEY);
> + return;
> + }
> +
> +spf_abort:
> + count_vm_event(SPF_ABORT);
> +#endif
> +
> /*
> * Kernel-mode access to the user address space should only occur
> * on well-defined single instructions listed in the exception
> @@ -1419,6 +1460,9 @@ void do_user_addr_fault(struct pt_regs *regs,
> }
>
> mmap_read_unlock(mm);
> +#ifdef CONFIG_SPECULATIVE_PAGE_FAULT
> +done:
> +#endif
> if (likely(!(fault & VM_FAULT_ERROR)))
> return;
>
> diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
> index b6678578a729..305f05d2a4bc 100644
> --- a/include/linux/mm_types.h
> +++ b/include/linux/mm_types.h
> @@ -370,6 +370,11 @@ struct anon_vma_name {
> * per VM-area/task. A VM area is any part of the process virtual memory
> * space that has a special rule for the page-fault handlers (ie a shared
> * library, the executable area etc).
> + *
> + * Note that speculative page faults make an on-stack copy of the VMA,
> + * so the structure size matters.
> + * (TODO - it would be preferable to copy only the required vma attributes
> + * rather than the entire vma).
> */
> struct vm_area_struct {
> /* The first cache line has the info for VMA tree walking. */
> diff --git a/include/linux/vm_event_item.h b/include/linux/vm_event_item.h
> index 7b2363388bfa..f00b3e36ff39 100644
> --- a/include/linux/vm_event_item.h
> +++ b/include/linux/vm_event_item.h
> @@ -133,6 +133,10 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT,
> #ifdef CONFIG_X86
> DIRECT_MAP_LEVEL2_SPLIT,
> DIRECT_MAP_LEVEL3_SPLIT,
> +#endif
> +#ifdef CONFIG_SPECULATIVE_PAGE_FAULT
> + SPF_ATTEMPT,
> + SPF_ABORT,
> #endif
> NR_VM_EVENT_ITEMS
> };
> diff --git a/mm/vmstat.c b/mm/vmstat.c
> index 4057372745d0..dbb0160e5558 100644
> --- a/mm/vmstat.c
> +++ b/mm/vmstat.c
> @@ -1390,6 +1390,10 @@ const char * const vmstat_text[] = {
> "direct_map_level2_splits",
> "direct_map_level3_splits",
> #endif
> +#ifdef CONFIG_SPECULATIVE_PAGE_FAULT
> + "spf_attempt",
> + "spf_abort",
> +#endif
> #endif /* CONFIG_VM_EVENT_COUNTERS || CONFIG_MEMCG */
> };
> #endif /* CONFIG_PROC_FS || CONFIG_SYSFS || CONFIG_NUMA || CONFIG_MEMCG */
> --
> 2.20.1
>
next prev parent reply other threads:[~2022-02-01 17:17 UTC|newest]
Thread overview: 67+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-28 13:09 [PATCH v2 00/35] Speculative page faults Michel Lespinasse
2022-01-28 13:09 ` [PATCH v2 01/35] mm: export dump_mm Michel Lespinasse
2022-01-28 13:09 ` [PATCH v2 02/35] mmap locking API: mmap_lock_is_contended returns a bool Michel Lespinasse
2022-01-28 13:09 ` [PATCH v2 03/35] mmap locking API: name the return values Michel Lespinasse
2022-01-31 16:17 ` Liam Howlett
2022-02-07 17:39 ` Michel Lespinasse
2022-01-28 13:09 ` [PATCH v2 04/35] do_anonymous_page: use update_mmu_tlb() Michel Lespinasse
2022-01-28 13:09 ` [PATCH v2 05/35] do_anonymous_page: reduce code duplication Michel Lespinasse
2022-01-28 13:09 ` [PATCH v2 06/35] mm: introduce CONFIG_SPECULATIVE_PAGE_FAULT Michel Lespinasse
2022-01-28 13:09 ` [PATCH v2 07/35] x86/mm: define ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT Michel Lespinasse
2022-01-28 13:09 ` [PATCH v2 08/35] mm: add FAULT_FLAG_SPECULATIVE flag Michel Lespinasse
2022-01-28 13:09 ` [PATCH v2 09/35] mm: add do_handle_mm_fault() Michel Lespinasse
2022-01-28 13:09 ` [PATCH v2 10/35] mm: add per-mm mmap sequence counter for speculative page fault handling Michel Lespinasse
2022-08-25 11:23 ` Pavan Kondeti
2022-01-28 13:09 ` [PATCH v2 11/35] mm: rcu safe vma freeing Michel Lespinasse
2022-01-28 13:09 ` [PATCH v2 12/35] mm: separate mmap locked assertion from find_vma Michel Lespinasse
2022-01-29 0:08 ` kernel test robot
2022-01-29 0:33 ` Michel Lespinasse
2022-01-31 14:44 ` Matthew Wilcox
2022-02-04 22:41 ` Michel Lespinasse
2022-01-28 13:09 ` [PATCH v2 13/35] x86/mm: attempt speculative mm faults first Michel Lespinasse
2022-02-01 17:16 ` Liam Howlett [this message]
2022-02-07 17:39 ` Michel Lespinasse
2022-01-28 13:09 ` [PATCH v2 14/35] mm: add speculative_page_walk_begin() and speculative_page_walk_end() Michel Lespinasse
2022-01-28 13:09 ` [PATCH v2 15/35] mm: refactor __handle_mm_fault() / handle_pte_fault() Michel Lespinasse
2022-01-28 13:09 ` [PATCH v2 16/35] mm: implement speculative handling in __handle_mm_fault() Michel Lespinasse
2022-01-28 13:09 ` [PATCH v2 17/35] mm: add pte_map_lock() and pte_spinlock() Michel Lespinasse
2022-01-28 13:09 ` [PATCH v2 18/35] mm: implement speculative handling in do_anonymous_page() Michel Lespinasse
2022-01-28 21:03 ` kernel test robot
2022-01-28 22:08 ` Michel Lespinasse
2022-01-30 2:54 ` [mm] fa5331bae2: canonical_address#:#[##] kernel test robot
2022-01-30 5:08 ` Michel Lespinasse
2022-01-28 13:09 ` [PATCH v2 19/35] mm: enable speculative fault handling through do_anonymous_page() Michel Lespinasse
2022-01-28 13:09 ` [PATCH v2 20/35] mm: implement speculative handling in do_numa_page() Michel Lespinasse
2022-01-28 13:09 ` [PATCH v2 21/35] mm: enable speculative fault " Michel Lespinasse
2022-01-28 13:09 ` [PATCH v2 22/35] percpu-rwsem: enable percpu_sem destruction in atomic context Michel Lespinasse
[not found] ` <20220129121319.3593-1-hdanton@sina.com>
2022-01-31 18:04 ` Suren Baghdasaryan
[not found] ` <20220201020958.3720-1-hdanton@sina.com>
2022-02-07 19:31 ` Suren Baghdasaryan
[not found] ` <20220208002059.2670-1-hdanton@sina.com>
2022-02-08 1:31 ` Suren Baghdasaryan
2022-01-28 13:09 ` [PATCH v2 23/35] mm: add mmu_notifier_lock Michel Lespinasse
2022-07-27 7:34 ` Pavan Kondeti
2022-07-27 20:30 ` Suren Baghdasaryan
2022-01-28 13:09 ` [PATCH v2 24/35] mm: write lock mmu_notifier_lock when registering mmu notifiers Michel Lespinasse
2022-01-28 13:09 ` [PATCH v2 25/35] mm: add mmu_notifier_trylock() and mmu_notifier_unlock() Michel Lespinasse
2022-01-28 13:09 ` [PATCH v2 26/35] mm: implement speculative handling in wp_page_copy() Michel Lespinasse
2022-01-28 13:09 ` [PATCH v2 27/35] mm: implement and enable speculative fault handling in handle_pte_fault() Michel Lespinasse
2022-01-28 13:09 ` [PATCH v2 28/35] mm: disable speculative faults for single threaded user space Michel Lespinasse
2022-01-28 13:10 ` [PATCH v2 29/35] mm: disable rcu safe vma freeing " Michel Lespinasse
2022-01-28 13:10 ` [PATCH v2 30/35] mm: create new include/linux/vm_event.h header file Michel Lespinasse
2022-01-28 13:10 ` [PATCH v2 31/35] mm: anon spf statistics Michel Lespinasse
2022-01-28 13:10 ` [PATCH v2 32/35] arm64/mm: define ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT Michel Lespinasse
2022-01-28 13:10 ` [PATCH v2 33/35] arm64/mm: attempt speculative mm faults first Michel Lespinasse
2022-01-30 9:13 ` Mike Rapoport
2022-01-31 8:07 ` Michel Lespinasse
2022-02-01 8:58 ` Mike Rapoport
2022-02-07 17:39 ` Michel Lespinasse
2022-02-08 9:07 ` Mike Rapoport
2022-01-28 13:10 ` [PATCH v2 34/35] powerpc/mm: define ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT Michel Lespinasse
2022-01-28 13:10 ` [PATCH v2 35/35] powerpc/mm: attempt speculative mm faults first Michel Lespinasse
2022-01-31 9:56 ` [PATCH v2 00/35] Speculative page faults David Hildenbrand
2022-01-31 17:00 ` Suren Baghdasaryan
2022-02-01 1:14 ` Andrew Morton
2022-02-01 2:20 ` Matthew Wilcox
2022-02-07 17:39 ` Michel Lespinasse
2022-02-01 17:17 ` Sebastian Andrzej Siewior
2022-02-23 16:11 ` Mel Gorman
2022-03-08 5:37 ` Suren Baghdasaryan
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20220201171617.z5zgafitgolyv5np@revolver \
--to=liam.howlett@oracle.com \
--cc=akpm@linux-foundation.org \
--cc=axelrasmussen@google.com \
--cc=dave@stgolabs.net \
--cc=jglisse@google.com \
--cc=joelaf@google.com \
--cc=kernel-team@fb.com \
--cc=ldufour@linux.ibm.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=luto@kernel.org \
--cc=mhocko@suse.com \
--cc=michel@lespinasse.org \
--cc=minchan@google.com \
--cc=paulmck@kernel.org \
--cc=peterz@infradead.org \
--cc=riel@surriel.com \
--cc=rientjes@google.com \
--cc=songliubraving@fb.com \
--cc=surenb@google.com \
--cc=vbabka@suse.cz \
--cc=willy@infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).