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Date: Tue, 9 Apr 2024 12:15:09 +0100
From: Catalin Marinas <catalin.marinas@arm.com>
To: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: akpm@linux-foundation.org, Russell King <linux@armlinux.org.uk>,
	Will Deacon <will@kernel.org>,
	Michael Ellerman <mpe@ellerman.id.au>,
	Nicholas Piggin <npiggin@gmail.com>,
	Christophe Leroy <christophe.leroy@csgroup.eu>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Albert Ou <aou@eecs.berkeley.edu>,
	Alexander Gordeev <agordeev@linux.ibm.com>,
	Gerald Schaefer <gerald.schaefer@linux.ibm.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Andy Lutomirski <luto@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>, x86@kernel.org,
	linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org,
	linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org,
	surenb@google.com, linux-mm@kvack.org
Subject: Re: [PATCH v2 2/7] arm64: mm: accelerate pagefault when
 VM_FAULT_BADACCESS
Message-ID: <ZhUjPZj5dij8JM9g@arm.com>
References: <20240403083805.1818160-1-wangkefeng.wang@huawei.com>
 <20240403083805.1818160-3-wangkefeng.wang@huawei.com>
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In-Reply-To: <20240403083805.1818160-3-wangkefeng.wang@huawei.com>

On Wed, Apr 03, 2024 at 04:38:00PM +0800, Kefeng Wang wrote:
> The vm_flags of vma already checked under per-VMA lock, if it is a
> bad access, directly set fault to VM_FAULT_BADACCESS and handle error,
> no need to retry with mmap_lock again, the latency time reduces 34% in
> 'lat_sig -P 1 prot lat_sig' from lmbench testcase.
> 
> Since the page faut is handled under per-VMA lock, count it as a vma lock
> event with VMA_LOCK_SUCCESS.
> 
> Reviewed-by: Suren Baghdasaryan <surenb@google.com>
> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>