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From: Nadav Amit <nadav.amit@gmail.com>
To: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Peter Xu <peterx@redhat.com>, Linux-MM <linux-mm@kvack.org>,
	kernel list <linux-kernel@vger.kernel.org>,
	Naoya Horiguchi <naoya.horiguchi@linux.dev>,
	David Hildenbrand <david@redhat.com>,
	Axel Rasmussen <axelrasmussen@google.com>,
	Mina Almasry <almasrymina@google.com>,
	Rik van Riel <riel@surriel.com>, Vlastimil Babka <vbabka@suse.cz>,
	Matthew Wilcox <willy@infradead.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Wei Chen <harperchen1110@gmail.com>,
	stable@vger.kernel.org
Subject: Re: [PATCH v2] hugetlb: don't delete vma_lock in hugetlb MADV_DONTNEED processing
Date: Sat, 29 Oct 2022 17:54:44 -0700	[thread overview]
Message-ID: <7048D2B5-5FA5-4F72-8FDC-A02411CFD71D@gmail.com> (raw)
In-Reply-To: <Y13CO8iIGfDnV24u@monkey>

On Oct 29, 2022, at 5:15 PM, Mike Kravetz <mike.kravetz@oracle.com> wrote:

> zap_page_range is a bit confusing.  It appears that the passed range can
> span multiple vmas.  Otherwise, there would be no do while loop.  Yet, there
> is only one mmu_notifier_range_init call specifying the passed vma.
> 
> It appears all callers pass a range entirely within a single vma.
> 
> The modifications above would work for a range within a single vma.  However,
> things would be more complicated if the range can indeed span multiple vmas.
> For multiple vmas, we would need to check the first and last vmas for
> pmd sharing.
> 
> Anyone know more about this seeming confusing behavior?  Perhaps, range
> spanning multiple vmas was left over earlier code?

I don’t have personal knowledge, but I noticed that it does not make much
sense, at least for MADV_DONTNEED. I tried to batch the TLB flushes across
VMAs for madvise’s. [1]

Need to get to it sometime.

[1] https://lore.kernel.org/lkml/20210926161259.238054-7-namit@vmware.com/



  reply	other threads:[~2022-10-30  0:54 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-10-23  2:50 Mike Kravetz
2022-10-24 21:55 ` Mike Kravetz
2022-10-24 23:14   ` Mike Kravetz
2022-10-26 21:42 ` Peter Xu
2022-10-26 23:54   ` Mike Kravetz
2022-10-27  1:12     ` Peter Xu
2022-10-28 15:23       ` Mike Kravetz
2022-10-28 16:13         ` Peter Xu
2022-10-28 21:17           ` Mike Kravetz
2022-10-28 23:20             ` Peter Xu
2022-10-30  0:15               ` Mike Kravetz
2022-10-30  0:54                 ` Nadav Amit [this message]
2022-10-30 18:43                   ` Peter Xu
2022-10-30 18:52                     ` Nadav Amit
2022-10-31  1:44                       ` Mike Kravetz
2022-11-02 19:24                         ` Peter Xu
2022-11-07 20:01                           ` Mike Kravetz

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