From: Matthew Wilcox <willy@infradead.org>
To: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: akpm@linux-foundation.org, arnd@arndb.de, muchun.song@linux.dev,
david@redhat.com, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org
Subject: Re: [PATCH 1/2] mm: pgtable: add missing flag and statistics for kernel PTE page
Date: Sun, 4 Feb 2024 18:51:05 +0000 [thread overview]
Message-ID: <Zb_cmZByel4cULDP@casper.infradead.org> (raw)
In-Reply-To: <f023a6687b9f2109401e7522b727aa4708dc05f1.1706774109.git.zhengqi.arch@bytedance.com>
On Thu, Feb 01, 2024 at 04:05:40PM +0800, Qi Zheng wrote:
> For kernel PTE page, we do not need to allocate and initialize its split
> ptlock, but as a page table page, it's still necessary to add PG_table
> flag and NR_PAGETABLE statistics for it.
No, this is wrong.
We do not account _kernel_ page tables to the _user_. Just because
the kernel, say, called vmalloc() doesn't mean we should charge the
task for it. Moreover, one task may call vmalloc() and a different task
would then call vfree().
This is a can of worms you don't want to open. Why did you want to do
this?
next prev parent reply other threads:[~2024-02-04 18:51 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-01 8:05 Qi Zheng
2024-02-01 8:05 ` [PATCH 2/2] mm: pgtable: remove unnecessary split ptlock for kernel PMD page Qi Zheng
2024-02-02 3:16 ` Muchun Song
2024-02-04 18:54 ` Matthew Wilcox
2024-02-05 2:14 ` Qi Zheng
2024-02-02 2:47 ` [PATCH 1/2] mm: pgtable: add missing flag and statistics for kernel PTE page Muchun Song
2024-02-04 10:58 ` Mike Rapoport
2024-02-04 11:39 ` Qi Zheng
2024-02-04 12:15 ` Mike Rapoport
2024-02-04 16:26 ` Qi Zheng
2024-02-04 18:51 ` Matthew Wilcox [this message]
2024-02-05 2:05 ` Qi Zheng
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