From: Matthew Wilcox <willy@infradead.org>
To: "zhangpeng (AS)" <zhangpeng362@huawei.com>
Cc: "Huang, Ying" <ying.huang@intel.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
akpm@linux-foundation.org, fengwei.yin@intel.com,
aneesh.kumar@linux.ibm.com, shy828301@gmail.com,
hughd@google.com, david@redhat.com, wangkefeng.wang@huawei.com,
sunnanyong@huawei.com
Subject: Re: [RFC PATCH] mm: filemap: avoid unnecessary major faults in filemap_fault()
Date: Thu, 23 Nov 2023 15:33:11 +0000 [thread overview]
Message-ID: <ZV9wt4+F/soWxVhR@casper.infradead.org> (raw)
In-Reply-To: <5b0e168a-dd43-80d4-2eeb-5c8a5d470f5e@huawei.com>
On Thu, Nov 23, 2023 at 05:09:04PM +0800, zhangpeng (AS) wrote:
> > > + pte_t *ptep = pte_offset_map_lock(vmf->vma->vm_mm, vmf->pmd,
> > > + vmf->address, &vmf->ptl);
> > > + if (ptep) {
> > > + /*
> > > + * Recheck pte with ptl locked as the pte can be cleared
> > > + * temporarily during a read/modify/write update.
> > > + */
> > > + if (unlikely(!pte_none(ptep_get(ptep))))
> > > + ret = VM_FAULT_NOPAGE;
> > > + pte_unmap_unlock(ptep, vmf->ptl);
> > > + if (unlikely(ret))
> > > + return ret;
> > > + }
> > > +
> > Need to deal with ptep == NULL. Although that is high impossible.
>
> If ptep == NULL, we may just need to return VM_FAULT_SIGBUS.
> I'll add it in the next version.
no? wouldn't ptep being NULL mean that the ptep has been replaced with
a PMD entry, and thus should return NOPAGE?
next prev parent reply other threads:[~2023-11-23 15:33 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-22 14:00 Peng Zhang
2023-11-23 1:09 ` Yin Fengwei
2023-11-23 4:12 ` zhangpeng (AS)
2023-11-23 5:26 ` Yin Fengwei
2023-11-23 7:57 ` zhangpeng (AS)
2023-11-23 8:29 ` Yin Fengwei
2023-11-23 9:09 ` zhangpeng (AS)
2023-11-24 4:13 ` Huang, Ying
2023-11-24 4:26 ` Huang, Ying
2023-11-24 7:27 ` zhangpeng (AS)
2023-11-24 8:04 ` Huang, Ying
2023-11-29 1:24 ` zhangpeng (AS)
2023-11-29 2:59 ` Huang, Ying
2024-02-01 12:10 ` zhangpeng (AS)
2024-02-02 0:39 ` Huang, Ying
2024-02-02 3:31 ` zhangpeng (AS)
2023-11-24 7:26 ` zhangpeng (AS)
2023-11-23 8:36 ` Huang, Ying
2023-11-23 9:09 ` zhangpeng (AS)
2023-11-23 15:33 ` Matthew Wilcox [this message]
2023-11-24 2:04 ` zhangpeng (AS)
2023-11-24 7:26 ` zhangpeng (AS)
2023-11-24 7:59 ` Huang, Ying
2023-11-24 6:05 ` Matthew Wilcox
2023-11-24 7:43 ` zhangpeng (AS)
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