From: Laurent Dufour <ldufour@linux.ibm.com>
To: Suren Baghdasaryan <surenb@google.com>, akpm@linux-foundation.org
Cc: michel@lespinasse.org, joelaf@google.com, songliubraving@fb.com,
mhocko@suse.com, david@redhat.com, peterz@infradead.org,
bigeasy@linutronix.de, peterx@redhat.com, dhowells@redhat.com,
linux-mm@kvack.org, jglisse@google.com, dave@stgolabs.net,
minchan@google.com, x86@kernel.org, hughd@google.com,
willy@infradead.org, laurent.dufour@fr.ibm.com, mgorman@suse.de,
rientjes@google.com, axelrasmussen@google.com,
kernel-team@android.com, paulmck@kernel.org,
liam.howlett@oracle.com, luto@kernel.org, vbabka@suse.cz,
linux-arm-kernel@lists.infradead.org, kent.overstreet@linux.dev,
linux-kernel@vger.kernel.org, hannes@cmpxchg.org,
linuxppc-dev@lists.ozlabs.org
Subject: Re: [RFC PATCH RESEND 21/28] mm: introduce find_and_lock_anon_vma to be used from arch-specific code
Date: Fri, 9 Sep 2022 16:38:27 +0200 [thread overview]
Message-ID: <630714df-dec1-4a41-6af3-380181d11669@linux.ibm.com> (raw)
In-Reply-To: <20220901173516.702122-22-surenb@google.com>
Le 01/09/2022 à 19:35, Suren Baghdasaryan a écrit :
> Introduce find_and_lock_anon_vma function to lookup and lock an anonymous
> VMA during page fault handling. When VMA is not found, can't be locked
> or changes after being locked, the function returns NULL. The lookup is
> performed under RCU protection to prevent the found VMA from being
> destroyed before the VMA lock is acquired. VMA lock statistics are
> updated according to the results.
>
> Signed-off-by: Suren Baghdasaryan <surenb@google.com>
> ---
> include/linux/mm.h | 3 +++
> mm/memory.c | 45 +++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 48 insertions(+)
>
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 7c3190eaabd7..a3cbaa7b9119 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -684,6 +684,9 @@ static inline void vma_assert_no_reader(struct vm_area_struct *vma)
> vma);
> }
>
> +struct vm_area_struct *find_and_lock_anon_vma(struct mm_struct *mm,
> + unsigned long address);
> +
> #else /* CONFIG_PER_VMA_LOCK */
>
> static inline void vma_init_lock(struct vm_area_struct *vma) {}
> diff --git a/mm/memory.c b/mm/memory.c
> index 29d2f49f922a..bf557f7056de 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -5183,6 +5183,51 @@ vm_fault_t handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
> }
> EXPORT_SYMBOL_GPL(handle_mm_fault);
>
> +#ifdef CONFIG_PER_VMA_LOCK
> +static inline struct vm_area_struct *find_vma_under_rcu(struct mm_struct *mm,
> + unsigned long address)
> +{
> + struct vm_area_struct *vma = __find_vma(mm, address);
> +
> + if (!vma || vma->vm_start > address)
> + return NULL;
> +
> + if (!vma_is_anonymous(vma))
> + return NULL;
> +
It looks to me more natural to first check that the VMA is part of the RB
tree before try read locking it.
> + if (!vma_read_trylock(vma)) {
> + count_vm_vma_lock_event(VMA_LOCK_ABORT);
> + return NULL;
> + }
> +
> + /* Check if the VMA got isolated after we found it */
> + if (RB_EMPTY_NODE(&vma->vm_rb)) {
> + vma_read_unlock(vma);
> + count_vm_vma_lock_event(VMA_LOCK_MISS);
> + return NULL;
> + }
> +
> + return vma;
> +}
> +
> +/*
> + * Lookup and lock and anonymous VMA. Returned VMA is guaranteed to be stable
> + * and not isolated. If the VMA is not found of is being modified the function
> + * returns NULL.
> + */
> +struct vm_area_struct *find_and_lock_anon_vma(struct mm_struct *mm,
> + unsigned long address)
> +{
> + struct vm_area_struct *vma;
> +
> + rcu_read_lock();
> + vma = find_vma_under_rcu(mm, address);
> + rcu_read_unlock();
> +
> + return vma;
> +}
> +#endif /* CONFIG_PER_VMA_LOCK */
> +
> #ifndef __PAGETABLE_P4D_FOLDED
> /*
> * Allocate p4d page table.
next prev parent reply other threads:[~2022-09-09 14:39 UTC|newest]
Thread overview: 91+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-01 17:34 [RFC PATCH RESEND 00/28] per-VMA locks proposal Suren Baghdasaryan
2022-09-01 17:34 ` [RFC PATCH RESEND 01/28] mm: introduce CONFIG_PER_VMA_LOCK Suren Baghdasaryan
2022-09-01 17:34 ` [RFC PATCH RESEND 02/28] mm: rcu safe VMA freeing Suren Baghdasaryan
2022-09-01 17:34 ` [RFC PATCH RESEND 03/28] mm: introduce __find_vma to be used without mmap_lock protection Suren Baghdasaryan
2022-09-01 20:22 ` Kent Overstreet
2022-09-01 23:18 ` Suren Baghdasaryan
2022-09-01 17:34 ` [RFC PATCH RESEND 04/28] mm: move mmap_lock assert function definitions Suren Baghdasaryan
2022-09-01 20:24 ` Kent Overstreet
2022-09-01 20:51 ` Liam Howlett
2022-09-01 23:21 ` Suren Baghdasaryan
2022-09-02 6:23 ` Sebastian Andrzej Siewior
2022-09-02 17:46 ` Suren Baghdasaryan
2022-09-01 17:34 ` [RFC PATCH RESEND 05/28] mm: add per-VMA lock and helper functions to control it Suren Baghdasaryan
2022-09-06 13:46 ` Laurent Dufour
2022-09-06 17:24 ` Suren Baghdasaryan
2022-09-01 17:34 ` [RFC PATCH RESEND 06/28] mm: mark VMA as locked whenever vma->vm_flags are modified Suren Baghdasaryan
2022-09-06 14:26 ` Laurent Dufour
2022-09-06 19:00 ` Suren Baghdasaryan
2022-09-06 20:00 ` Liam Howlett
2022-09-06 20:13 ` Suren Baghdasaryan
2022-09-01 17:34 ` [RFC PATCH RESEND 07/28] kernel/fork: mark VMAs as locked before copying pages during fork Suren Baghdasaryan
2022-09-06 14:37 ` Laurent Dufour
2022-09-08 23:57 ` Suren Baghdasaryan
2022-09-09 13:27 ` Laurent Dufour
2022-09-09 16:29 ` Suren Baghdasaryan
2022-09-01 17:34 ` [RFC PATCH RESEND 08/28] mm/khugepaged: mark VMA as locked while collapsing a hugepage Suren Baghdasaryan
2022-09-06 14:43 ` Laurent Dufour
2022-09-09 0:15 ` Suren Baghdasaryan
2022-09-01 17:34 ` [RFC PATCH RESEND 09/28] mm/mempolicy: mark VMA as locked when changing protection policy Suren Baghdasaryan
2022-09-06 14:47 ` Laurent Dufour
2022-09-09 0:27 ` Suren Baghdasaryan
2022-09-01 17:34 ` [RFC PATCH RESEND 10/28] mm/mmap: mark VMAs as locked in vma_adjust Suren Baghdasaryan
2022-09-06 15:35 ` Laurent Dufour
2022-09-09 0:51 ` Suren Baghdasaryan
2022-09-09 15:52 ` Laurent Dufour
2022-09-01 17:34 ` [RFC PATCH RESEND 11/28] mm/mmap: mark VMAs as locked before merging or splitting them Suren Baghdasaryan
2022-09-06 15:44 ` Laurent Dufour
2022-09-01 17:35 ` [RFC PATCH RESEND 12/28] mm/mremap: mark VMA as locked while remapping it to a new address range Suren Baghdasaryan
2022-09-06 16:09 ` Laurent Dufour
2022-09-01 17:35 ` [RFC PATCH RESEND 13/28] mm: conditionally mark VMA as locked in free_pgtables and unmap_page_range Suren Baghdasaryan
2022-09-09 10:33 ` Laurent Dufour
2022-09-09 16:43 ` Suren Baghdasaryan
2022-09-01 17:35 ` [RFC PATCH RESEND 14/28] mm: mark VMAs as locked before isolating them Suren Baghdasaryan
2022-09-09 13:35 ` Laurent Dufour
2022-09-09 16:28 ` Suren Baghdasaryan
2022-09-01 17:35 ` [RFC PATCH RESEND 15/28] mm/mmap: mark adjacent VMAs as locked if they can grow into unmapped area Suren Baghdasaryan
2022-09-09 13:43 ` Laurent Dufour
2022-09-09 16:25 ` Suren Baghdasaryan
2022-09-01 17:35 ` [RFC PATCH RESEND 16/28] kernel/fork: assert no VMA readers during its destruction Suren Baghdasaryan
2022-09-09 13:56 ` Laurent Dufour
2022-09-09 16:19 ` Suren Baghdasaryan
2022-09-01 17:35 ` [RFC PATCH RESEND 17/28] mm/mmap: prevent pagefault handler from racing with mmu_notifier registration Suren Baghdasaryan
2022-09-09 14:20 ` Laurent Dufour
2022-09-09 16:12 ` Suren Baghdasaryan
2022-09-01 17:35 ` [RFC PATCH RESEND 18/28] mm: add FAULT_FLAG_VMA_LOCK flag Suren Baghdasaryan
2022-09-09 14:26 ` Laurent Dufour
2022-09-01 17:35 ` [RFC PATCH RESEND 19/28] mm: disallow do_swap_page to handle page faults under VMA lock Suren Baghdasaryan
2022-09-06 19:39 ` Peter Xu
2022-09-06 20:08 ` Suren Baghdasaryan
2022-09-06 20:22 ` Peter Xu
2022-09-07 0:58 ` Suren Baghdasaryan
2022-09-09 14:26 ` Laurent Dufour
2022-09-01 17:35 ` [RFC PATCH RESEND 20/28] mm: introduce per-VMA lock statistics Suren Baghdasaryan
2022-09-09 14:28 ` Laurent Dufour
2022-09-09 16:11 ` Suren Baghdasaryan
2022-09-01 17:35 ` [RFC PATCH RESEND 21/28] mm: introduce find_and_lock_anon_vma to be used from arch-specific code Suren Baghdasaryan
2022-09-09 14:38 ` Laurent Dufour [this message]
2022-09-09 16:10 ` Suren Baghdasaryan
2022-09-01 17:35 ` [RFC PATCH RESEND 22/28] x86/mm: try VMA lock-based page fault handling first Suren Baghdasaryan
2022-09-01 17:35 ` [RFC PATCH RESEND 23/28] x86/mm: define ARCH_SUPPORTS_PER_VMA_LOCK Suren Baghdasaryan
2022-09-01 20:20 ` Kent Overstreet
2022-09-01 23:17 ` Suren Baghdasaryan
2022-09-01 17:35 ` [RFC PATCH RESEND 24/28] arm64/mm: try VMA lock-based page fault handling first Suren Baghdasaryan
2022-09-01 17:35 ` [RFC PATCH RESEND 25/28] arm64/mm: define ARCH_SUPPORTS_PER_VMA_LOCK Suren Baghdasaryan
2022-09-01 17:35 ` [RFC PATCH RESEND 26/28] powerc/mm: try VMA lock-based page fault handling first Suren Baghdasaryan
2022-09-01 17:35 ` [RFC PATCH RESEND 27/28] powerpc/mm: define ARCH_SUPPORTS_PER_VMA_LOCK Suren Baghdasaryan
2022-09-01 17:35 ` [RFC PATCH RESEND 28/28] kernel/fork: throttle call_rcu() calls in vm_area_free Suren Baghdasaryan
2022-09-09 15:19 ` Laurent Dufour
2022-09-09 16:02 ` Suren Baghdasaryan
2022-09-09 16:14 ` Laurent Dufour
2022-09-01 20:58 ` [RFC PATCH RESEND 00/28] per-VMA locks proposal Kent Overstreet
2022-09-01 23:26 ` Suren Baghdasaryan
2022-09-11 9:35 ` Vlastimil Babka
2022-09-28 2:28 ` Suren Baghdasaryan
2022-09-29 11:18 ` Vlastimil Babka
2022-09-02 7:42 ` Peter Zijlstra
2022-09-02 14:45 ` Suren Baghdasaryan
2022-09-05 12:32 ` Michal Hocko
2022-09-05 18:32 ` Suren Baghdasaryan
2022-09-05 20:35 ` Kent Overstreet
2022-09-06 15:46 ` Suren Baghdasaryan
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