[<prev] [next>] [<thread-prev] [day] [month] [year] [list]
Message-ID: <31813228-4d2e-45f5-98d3-10cae826130a@redhat.com>
Date: Fri, 26 Apr 2024 19:36:31 +0200
From: David Hildenbrand <david@...hat.com>
To: "Matthew Wilcox (Oracle)" <willy@...radead.org>,
Andrew Morton <akpm@...ux-foundation.org>
Cc: linux-mm@...ck.org, linux-kernel@...r.kernel.org,
Suren Baghdasaryan <surenb@...gle.com>, Peter Xu <peterx@...hat.com>,
Jann Horn <jannh@...gle.com>
Subject: Re: [PATCH 4/4] mm: Optimise vmf_anon_prepare() for VMAs without an
anon_vma
On 26.04.24 16:45, Matthew Wilcox (Oracle) wrote:
> If the mmap_lock can be taken for read, we can call __anon_vma_prepare()
> while holding it, saving ourselves a trip back through the fault handler.
>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>
> Reviewed-by: Jann Horn <jannh@...gle.com>
> Reviewed-by: Suren Baghdasaryan <surenb@...gle.com>
> ---
> mm/memory.c | 13 +++++++++----
> 1 file changed, 9 insertions(+), 4 deletions(-)
>
> diff --git a/mm/memory.c b/mm/memory.c
> index 7dc112d3a7e4..b5453b86ec4b 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -3232,16 +3232,21 @@ static inline vm_fault_t vmf_can_call_fault(const struct vm_fault *vmf)
> vm_fault_t vmf_anon_prepare(struct vm_fault *vmf)
> {
> struct vm_area_struct *vma = vmf->vma;
> + vm_fault_t ret = 0;
>
> if (likely(vma->anon_vma))
> return 0;
> if (vmf->flags & FAULT_FLAG_VMA_LOCK) {
> - vma_end_read(vma);
> - return VM_FAULT_RETRY;
> + if (!mmap_read_trylock(vma->vm_mm)) {
> + vma_end_read(vma);
> + return VM_FAULT_RETRY;
> + }
> }
> if (__anon_vma_prepare(vma))
> - return VM_FAULT_OOM;
> - return 0;
> + ret = VM_FAULT_OOM;
> + if (vmf->flags & FAULT_FLAG_VMA_LOCK)
> + mmap_read_unlock(vma->vm_mm);
> + return ret;
> }
>
> /*
Fancy
Reviewed-by: David Hildenbrand <david@...hat.com>
--
Cheers,
David / dhildenb
Powered by blists - more mailing lists