From: Alex Shi <alex.shi@linux.alibaba.com>
To: "Mika Penttilä" <mika.penttila@nextfour.com>,
"Kirill A. Shutemov" <kirill@shutemov.name>,
"Matthew Wilcox" <willy@infradead.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>,
Linux-MM <linux-mm@kvack.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Hugh Dickins <hughd@google.com>
Subject: Re: a question of split_huge_page
Date: Fri, 10 Jul 2020 15:00:40 +0800 [thread overview]
Message-ID: <b6faa876-4c20-e99f-2e41-770871a5403d@linux.alibaba.com> (raw)
In-Reply-To: <441ebbeb-0408-e22e-20f4-1be571c4a18e@nextfour.com>
在 2020/7/10 下午1:28, Mika Penttilä 写道:
>> Thanks a lot for quick reply!
>> What I am confusing is the call chain: __iommu_dma_alloc_pages()
>> to split_huge_page(), in the func, splited page,
>> page = alloc_pages_node(nid, alloc_flags, order);
>> And if the pages were added into lru, they maybe reclaimed and lost,
>> that would be a panic bug. But in fact, this never happened for long time.
>> Also I put a BUG() at the line, it's nevre triggered in ltp, and run_vmtests
>
> In __iommu_dma_alloc_pages, after split_huge_page(), who is taking a
> reference on tail pages? Seems tail pages are freed and the function
> errornously returns them in pages[] array for use?
>
Why you say so? It looks like the tail page returned and be used
pages = __iommu_dma_alloc_pages() in iommu_dma_alloc_remap()
and still on node's lru. Is this right?
thanks!
next prev parent reply other threads:[~2020-07-10 7:01 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-09 15:11 a question of split_huge_page Alex Shi
2020-07-09 15:50 ` Matthew Wilcox
2020-07-09 16:07 ` Kirill A. Shutemov
2020-07-10 4:51 ` Alex Shi
2020-07-10 5:28 ` Mika Penttilä
2020-07-10 7:00 ` Alex Shi [this message]
2020-07-10 7:22 ` Mika Penttilä
2020-07-10 9:34 ` Alex Shi
2020-07-10 12:56 ` Joerg Roedel
2020-07-10 17:29 ` Yang Shi
2020-07-10 10:33 ` Kirill A. Shutemov
2020-07-10 14:23 ` Alex Shi
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