From: Andrew Morton <akpm@linux-foundation.org>
To: Bibo Mao <maobibo@loongson.cn>
Cc: "Thomas Bogendoerfer" <tsbogend@alpha.franken.de>,
"Jiaxun Yang" <jiaxun.yang@flygoat.com>,
"Huacai Chen" <chenhc@lemote.com>,
"Paul Burton" <paulburton@kernel.org>,
"Dmitry Korotin" <dkorotin@wavecomp.com>,
"Philippe Mathieu-Daudé" <f4bug@amsat.org>,
"Stafford Horne" <shorne@gmail.com>,
"Steven Price" <steven.price@arm.com>,
"Anshuman Khandual" <anshuman.khandual@arm.com>,
linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org,
"Mike Rapoport" <rppt@linux.ibm.com>,
"Sergei Shtylyov" <sergei.shtylyov@cogentembedded.com>,
"Maciej W. Rozycki" <macro@wdc.com>,
linux-mm@kvack.org, "David Hildenbrand" <david@redhat.com>
Subject: Re: [PATCH v7 2/4] mm/memory.c: Update local TLB if PTE entry exists
Date: Thu, 28 May 2020 12:23:42 -0700 [thread overview]
Message-ID: <20200528122342.11e51dd9c7698d68632f2a81@linux-foundation.org> (raw)
In-Reply-To: <1590546320-21814-3-git-send-email-maobibo@loongson.cn>
On Wed, 27 May 2020 10:25:18 +0800 Bibo Mao <maobibo@loongson.cn> wrote:
> If two threads concurrently fault at the same page, the thread that
> won the race updates the PTE and its local TLB. For now, the other
> thread gives up, simply does nothing, and continues.
>
> It could happen that this second thread triggers another fault, whereby
> it only updates its local TLB while handling the fault. Instead of
> triggering another fault, let's directly update the local TLB of the
> second thread. Function update_mmu_tlb is used here to update local
> TLB on the second thread, and it is defined as empty on other arches.
>
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -2752,6 +2752,7 @@ static vm_fault_t wp_page_copy(struct vm_fault *vmf)
> new_page = old_page;
> page_copied = 1;
> } else {
> + update_mmu_tlb(vma, vmf->address, vmf->pte);
> mem_cgroup_cancel_charge(new_page, memcg, false);
> }
>
When applying your patches on top of the -mm tree's changes, the above
hunk didn't apply. The entire `else' block was removed by
https://ozlabs.org/~akpm/mmotm/broken-out/mm-memcontrol-convert-anon-and-file-thp-to-new-mem_cgroup_charge-api.patch
I assumed that dropping this hunk was appropriate. Please check?
next prev parent reply other threads:[~2020-05-28 19:23 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-27 2:25 [PATCH v7 0/4] MIPS: page fault handling optimization Bibo Mao
2020-05-27 2:25 ` [PATCH v7 1/4] MIPS: Do not flush tlb page when updating PTE entry Bibo Mao
2020-05-27 2:25 ` [PATCH v7 2/4] mm/memory.c: Update local TLB if PTE entry exists Bibo Mao
2020-05-28 19:23 ` Andrew Morton [this message]
2020-05-29 0:59 ` maobibo
2020-05-27 2:25 ` [PATCH v7 3/4] mm/memory.c: Add memory read privilege on page fault handling Bibo Mao
2020-05-27 2:25 ` [PATCH v7 4/4] MIPS: mm: add page valid judgement in function pte_modify Bibo Mao
2020-05-27 11:32 ` [PATCH v7 0/4] MIPS: page fault handling optimization Thomas Bogendoerfer
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