From: Matthew Wilcox <willy@infradead.org>
To: Minchan Kim <minchan@kernel.org>
Cc: Jan Kara <jack@suse.cz>,
Andrew Morton <akpm@linux-foundation.org>,
linux-mm <linux-mm@kvack.org>, Josef Bacik <josef@toxicpanda.com>,
Johannes Weiner <hannes@cmpxchg.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] mm: fix long time stall from mm_populate
Date: Wed, 12 Feb 2020 10:28:51 -0800 [thread overview]
Message-ID: <20200212182851.GG7778@bombadil.infradead.org> (raw)
In-Reply-To: <20200212174015.GB93795@google.com>
On Wed, Feb 12, 2020 at 09:40:15AM -0800, Minchan Kim wrote:
> How about this?
>
> diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
> index 1bf83c8fcaa7..d07d602476df 100644
> --- a/include/linux/page-flags.h
> +++ b/include/linux/page-flags.h
> @@ -363,8 +363,28 @@ PAGEFLAG(MappedToDisk, mappedtodisk, PF_NO_TAIL)
> /* PG_readahead is only used for reads; PG_reclaim is only for writes */
> PAGEFLAG(Reclaim, reclaim, PF_NO_TAIL)
> TESTCLEARFLAG(Reclaim, reclaim, PF_NO_TAIL)
> -PAGEFLAG(Readahead, reclaim, PF_NO_COMPOUND)
> - TESTCLEARFLAG(Readahead, reclaim, PF_NO_COMPOUND)
> +
> +SETPAGEFLAG(Readahead, reclaim, PF_NO_COMPOUND)
> +CLEARPAGEFLAG(Readahead, reclaim, PF_NO_COMPOUND)
> +
> +/*
> + * Since PG_readahead is shared with PG_reclaim of the page flags,
> + * PageReadahead should double check whether it's readahead marker
> + * or PG_reclaim. It could be done by PageWriteback check because
> + * PG_reclaim is always with PG_writeback.
> + */
> +static inline int PageReadahead(struct page *page)
> +{
> + VM_BUG_ON_PGFLAGS(PageCompound(page), page);
> + return test_bit(PG_reclaim, &(page)->flags) && !PageWriteback(page);
Why not ...
return page->flags & (1UL << PG_reclaim | 1UL << PG_writeback) ==
(1UL << PG_reclaim);
> +static inline int TestClearPageReadahead(struct page *page)
> +{
> + VM_BUG_ON_PGFLAGS(PageCompound(page), page);
> +
> + return test_and_clear_bit(PG_reclaim, &page->flags) && !PageWriteback(page);
That's definitely wrong. It'll clear PageReclaim and then pretend it did
nothing wrong.
return !PageWriteback(page) ||
test_and_clear_bit(PG_reclaim, &page->flags);
next prev parent reply other threads:[~2020-02-12 18:28 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-11 0:19 [PATCH] mm: fix long time stall from mm_populate Minchan Kim
2020-02-11 1:10 ` Matthew Wilcox
2020-02-11 3:50 ` Minchan Kim
2020-02-11 3:54 ` Matthew Wilcox
2020-02-11 4:25 ` Minchan Kim
2020-02-11 12:23 ` Matthew Wilcox
2020-02-11 16:34 ` Minchan Kim
2020-02-11 17:28 ` Matthew Wilcox
2020-02-11 17:57 ` Minchan Kim
2020-02-12 10:18 ` Jan Kara
2020-02-12 17:40 ` Minchan Kim
2020-02-12 18:28 ` Matthew Wilcox [this message]
2020-02-12 19:53 ` Minchan Kim
2020-02-12 22:24 ` Andrew Morton
2020-02-12 23:12 ` Minchan Kim
2020-02-13 2:00 ` Andrew Morton
2020-02-13 17:24 ` Minchan Kim
2020-02-11 18:14 ` Yang Shi
2020-02-12 10:22 ` Jan Kara
2020-02-12 17:43 ` Minchan Kim
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