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From: Matthew Wilcox <willy@infradead.org>
To: Minchan Kim <minchan@kernel.org>
Cc: "Yu Zhao" <yuzhao@google.com>,
	"Yin, Fengwei" <fengwei.yin@intel.com>,
	"Yang Shi" <shy828301@gmail.com>,
	"Andrew Morton" <akpm@linux-foundation.org>,
	Linux-MM <linux-mm@kvack.org>, 韩天硕 <hantianshuo@iie.ac.cn>,
	mawupeng <mawupeng1@huawei.com>
Subject: Re: (resend)WARNING: trying to isolate tail page in isolate_lru_page
Date: Fri, 26 Aug 2022 19:02:48 +0100	[thread overview]
Message-ID: <YwkKyBPeDbZc3r8J@casper.infradead.org> (raw)
In-Reply-To: <YwkIqt3T6y/jJizP@google.com>

On Fri, Aug 26, 2022 at 10:53:46AM -0700, Minchan Kim wrote:
> Long term, that's better idea(For stable backport, I'd like to go with
> simple PageLRU check).
> 
> I wonder it's possible to mix LRU pages and non-struct pages together
> in a VMA. Otherwise, could we reuse(abuse) VM_MIXEDMAP?

On a bit of a tangent, I'm not sure that we should be allowing this for
file pages at all.  I see that we only allow it if mapcount is 1, but page
cache is also used by applications that don't mmap it.  So if some other
application is using /tmp/bigfile with read() and write(), I can force
that memory out of the page cache by mmaping it and calling MADV_PAGEOUT.
That could be used as an exfiltration side-channel, for example.



  parent reply	other threads:[~2022-08-26 18:03 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-08-25 14:40 韩天硕
2022-08-25 16:50 ` Yu Zhao
2022-08-25 18:23   ` Matthew Wilcox
2022-08-25 18:37     ` Yu Zhao
2022-08-25 18:40     ` Yang Shi
2022-08-25 18:46       ` Matthew Wilcox
2022-08-26  3:20         ` Yin, Fengwei
2022-08-26 16:56           ` Minchan Kim
2022-08-26 18:23             ` Yang Shi
2022-08-26 22:58               ` Minchan Kim
2022-08-27  0:48             ` Yin, Fengwei
2022-08-26 17:15           ` Matthew Wilcox
2022-08-26 17:27             ` Yu Zhao
2022-08-26 17:53               ` Minchan Kim
2022-08-26 17:58                 ` Yu Zhao
2022-08-26 18:02                 ` Matthew Wilcox [this message]
2022-08-26 18:19                 ` Yang Shi
2022-08-26 23:12                   ` Minchan Kim
2022-08-27  0:24             ` Yin, Fengwei

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