From: Anshuman Khandual <anshuman.khandual@arm.com>
To: Bibo Mao <maobibo@loongson.cn>,
Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm: add access/dirty bit on numa page fault
Date: Wed, 16 Mar 2022 12:13:07 +0530 [thread overview]
Message-ID: <93302a47-9fda-25c7-4212-41b8dd027696@arm.com> (raw)
In-Reply-To: <20220316010836.1137084-1-maobibo@loongson.cn>
On 3/16/22 06:38, Bibo Mao wrote:
> During numa page fault, dirty bit can be added for old pte if
> fail to migrate on write fault. And if it succeeds to migrate,
> access bit can be added for migrated new pte, also dirty bit
> can be added for write fault.
The current code does not set the access and dirty bits when ever
applicable i.e on FAULT_FLAG_WRITE, on the pte (old if migration
fails, new if migration succeeds) ? Did not this cause any problem
earlier ? I am wondering how this might have gone unnoticed.
>
> Signed-off-by: Bibo Mao <maobibo@loongson.cn>
> ---
> mm/memory.c | 21 ++++++++++++++++++++-
> 1 file changed, 20 insertions(+), 1 deletion(-)
>
> diff --git a/mm/memory.c b/mm/memory.c
> index c125c4969913..65813bec9c06 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -4404,6 +4404,22 @@ static vm_fault_t do_numa_page(struct vm_fault *vmf)
> if (migrate_misplaced_page(page, vma, target_nid)) {
> page_nid = target_nid;
> flags |= TNF_MIGRATED;
> +
> + /*
> + * update pte entry with access bit, and dirty bit for
> + * write fault
> + */
> + spin_lock(vmf->ptl);
> + pte = *vmf->pte;
> + pte = pte_mkyoung(pte);
> + if (was_writable) {
> + pte = pte_mkwrite(pte);
> + if (vmf->flags & FAULT_FLAG_WRITE)
> + pte = pte_mkdirty(pte);
> + }
> + set_pte_at(vma->vm_mm, vmf->address, vmf->pte, pte);
> + update_mmu_cache(vma, vmf->address, vmf->pte);
> + pte_unmap_unlock(vmf->pte, vmf->ptl);
> } else {
> flags |= TNF_MIGRATE_FAIL;
> vmf->pte = pte_offset_map(vmf->pmd, vmf->address);
> @@ -4427,8 +4443,11 @@ static vm_fault_t do_numa_page(struct vm_fault *vmf)
> old_pte = ptep_modify_prot_start(vma, vmf->address, vmf->pte);
> pte = pte_modify(old_pte, vma->vm_page_prot);
> pte = pte_mkyoung(pte);
> - if (was_writable)
> + if (was_writable) {
> pte = pte_mkwrite(pte);
> + if (vmf->flags & FAULT_FLAG_WRITE)
> + pte = pte_mkdirty(pte);
> + }
> ptep_modify_prot_commit(vma, vmf->address, vmf->pte, old_pte, pte);
> update_mmu_cache(vma, vmf->address, vmf->pte);
> pte_unmap_unlock(vmf->pte, vmf->ptl);
next prev parent reply other threads:[~2022-03-16 6:43 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-16 1:08 [PATCH] mm: add access/dirty bit on numa page fault Bibo Mao
2022-03-16 6:43 ` Anshuman Khandual [this message]
2022-03-16 7:03 ` maobibo
2022-03-16 9:42 ` Anshuman Khandual
2022-03-17 1:09 ` maobibo
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