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From: Matthew Wilcox <willy@infradead.org>
To: "Huang, Ying" <ying.huang@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
	Andrea Arcangeli <aarcange@redhat.com>,
	Michal Hocko <mhocko@suse.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Shaohua Li <shli@kernel.org>, Hugh Dickins <hughd@google.com>,
	Minchan Kim <minchan@kernel.org>, Rik van Riel <riel@redhat.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
	Zi Yan <zi.yan@cs.rutgers.edu>,
	Daniel Jordan <daniel.m.jordan@oracle.com>
Subject: Re: [PATCH -mm -v4 08/21] mm, THP, swap: Support to read a huge swap cluster for swapin a THP
Date: Thu, 28 Jun 2018 23:21:26 -0700	[thread overview]
Message-ID: <20180629062126.GJ7646@bombadil.infradead.org> (raw)
In-Reply-To: <20180622035151.6676-9-ying.huang@intel.com>

On Fri, Jun 22, 2018 at 11:51:38AM +0800, Huang, Ying wrote:
> +++ b/mm/swap_state.c
> @@ -426,33 +447,37 @@ struct page *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
>  		/*
>  		 * call radix_tree_preload() while we can wait.
>  		 */
> -		err = radix_tree_maybe_preload(gfp_mask & GFP_KERNEL);
> +		err = radix_tree_maybe_preload_order(gfp_mask & GFP_KERNEL,
> +						     compound_order(new_page));
>  		if (err)
>  			break;

There's no more preloading in the XArray world, so this can just be dropped.

>  		/*
>  		 * Swap entry may have been freed since our caller observed it.
>  		 */
> +		err = swapcache_prepare(hentry, huge_cluster);
> +		if (err) {
>  			radix_tree_preload_end();
> -			break;
> +			if (err == -EEXIST) {
> +				/*
> +				 * We might race against get_swap_page() and
> +				 * stumble across a SWAP_HAS_CACHE swap_map
> +				 * entry whose page has not been brought into
> +				 * the swapcache yet.
> +				 */
> +				cond_resched();
> +				continue;
> +			} else if (err == -ENOTDIR) {
> +				/* huge swap cluster is split under us */
> +				continue;
> +			} else		/* swp entry is obsolete ? */
> +				break;

I'm not entirely happy about -ENOTDIR being overloaded to mean this.
Maybe we can return a new enum rather than an errno?

Also, I'm not sure that a true/false parameter is the right approach for
"is this a huge page".  I think we'll have usecases for swap entries which
are both larger and smaller than PMD_SIZE.

I was hoping to encode the swap entry size into the entry; we only need one
extra bit to do that (no matter the size of the entry).  I detailed the
encoding scheme here:

https://plus.google.com/117536210417097546339/posts/hvctn17WUZu

(let me know if that doesn't work for you; I'm not very experienced with
this G+ thing)

  reply	other threads:[~2018-06-29  6:21 UTC|newest]

Thread overview: 100+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-06-22  3:51 [PATCH -mm -v4 00/21] mm, THP, swap: Swapout/swapin THP in one piece Huang, Ying
2018-06-22  3:51 ` Huang, Ying
2018-06-22  3:51 ` [PATCH -mm -v4 01/21] mm, THP, swap: Enable PMD swap operations for CONFIG_THP_SWAP Huang, Ying
2018-07-07 21:11   ` Dan Williams
2018-07-09  5:40     ` Huang, Ying
2018-07-09  5:40       ` Huang, Ying
2018-07-09  6:08       ` Dan Williams
2018-07-09  6:34         ` Huang, Ying
2018-07-09  6:34           ` Huang, Ying
2018-07-09 15:59   ` Dave Hansen
2018-07-10  1:08     ` Huang, Ying
2018-07-10  1:08       ` Huang, Ying
2018-06-22  3:51 ` [PATCH -mm -v4 02/21] mm, THP, swap: Make CONFIG_THP_SWAP depends on CONFIG_SWAP Huang, Ying
2018-07-07 21:12   ` Dan Williams
2018-07-09  6:34     ` Huang, Ying
2018-07-09  6:34       ` Huang, Ying
2018-07-09 16:00   ` Dave Hansen
2018-07-10  1:19     ` Huang, Ying
2018-07-10  1:19       ` Huang, Ying
2018-07-10  1:59       ` Dave Hansen
2018-07-10  5:26         ` Huang, Ying
2018-07-10  5:26           ` Huang, Ying
2018-06-22  3:51 ` [PATCH -mm -v4 03/21] mm, THP, swap: Support PMD swap mapping in swap_duplicate() Huang, Ying
2018-06-29  6:04   ` Matthew Wilcox
2018-07-02  5:19     ` Huang, Ying
2018-07-02  5:19       ` Huang, Ying
2018-07-07 23:22   ` Dan Williams
2018-07-09  7:38     ` Huang, Ying
2018-07-09  7:38       ` Huang, Ying
2018-07-09 16:51   ` Dave Hansen
2018-07-10  6:44     ` Huang, Ying
2018-07-10  6:44       ` Huang, Ying
2018-07-10 13:50       ` Dave Hansen
2018-07-11  0:59         ` Huang, Ying
2018-07-11  0:59           ` Huang, Ying
2018-06-22  3:51 ` [PATCH -mm -v4 04/21] mm, THP, swap: Support PMD swap mapping in swapcache_free_cluster() Huang, Ying
2018-07-09 17:11   ` Dave Hansen
2018-07-10  6:53     ` Huang, Ying
2018-07-10  6:53       ` Huang, Ying
2018-07-10 13:54       ` Dave Hansen
2018-07-11  1:08         ` Huang, Ying
2018-07-11  1:08           ` Huang, Ying
2018-06-22  3:51 ` [PATCH -mm -v4 05/21] mm, THP, swap: Support PMD swap mapping in free_swap_and_cache()/swap_free() Huang, Ying
2018-07-05 18:33   ` Daniel Jordan
2018-07-06 12:49     ` Huang, Ying
2018-07-06 12:49       ` Huang, Ying
2018-07-09 17:19   ` Dave Hansen
2018-07-10  7:13     ` Huang, Ying
2018-07-10  7:13       ` Huang, Ying
2018-07-10 14:07       ` Dave Hansen
2018-07-11  1:28         ` Huang, Ying
2018-07-11  1:28           ` Huang, Ying
2018-06-22  3:51 ` [PATCH -mm -v4 06/21] mm, THP, swap: Support PMD swap mapping when splitting huge PMD Huang, Ying
2018-06-22  3:51 ` [PATCH -mm -v4 07/21] mm, THP, swap: Support PMD swap mapping in split_swap_cluster() Huang, Ying
2018-06-22  3:51 ` [PATCH -mm -v4 08/21] mm, THP, swap: Support to read a huge swap cluster for swapin a THP Huang, Ying
2018-06-29  6:21   ` Matthew Wilcox [this message]
2018-07-02  6:02     ` Huang, Ying
2018-07-02  6:02       ` Huang, Ying
2018-07-04  0:12   ` Daniel Jordan
2018-07-04  2:24     ` Huang, Ying
2018-07-04  2:24       ` Huang, Ying
2018-06-22  3:51 ` [PATCH -mm -v4 09/21] mm, THP, swap: Swapin a THP as a whole Huang, Ying
2018-06-22  3:51 ` [PATCH -mm -v4 10/21] mm, THP, swap: Support to count THP swapin and its fallback Huang, Ying
2018-06-22  3:51 ` [PATCH -mm -v4 11/21] mm, THP, swap: Add sysfs interface to configure THP swapin Huang, Ying
2018-06-22  3:51 ` [PATCH -mm -v4 12/21] mm, THP, swap: Support PMD swap mapping in swapoff Huang, Ying
2018-06-22  3:51 ` [PATCH -mm -v4 13/21] mm, THP, swap: Support PMD swap mapping in madvise_free() Huang, Ying
2018-06-22  3:51 ` [PATCH -mm -v4 14/21] mm, cgroup, THP, swap: Support to move swap account for PMD swap mapping Huang, Ying
2018-07-09 17:20   ` Daniel Jordan
2018-07-10  7:49     ` Huang, Ying
2018-07-10  7:49       ` Huang, Ying
2018-07-10 22:49       ` Daniel Jordan
2018-06-22  3:51 ` [PATCH -mm -v4 15/21] mm, THP, swap: Support to copy PMD swap mapping when fork() Huang, Ying
2018-06-22  3:51 ` [PATCH -mm -v4 16/21] mm, THP, swap: Free PMD swap mapping when zap_huge_pmd() Huang, Ying
2018-06-22  3:51 ` [PATCH -mm -v4 17/21] mm, THP, swap: Support PMD swap mapping for MADV_WILLNEED Huang, Ying
2018-06-22  3:51 ` [PATCH -mm -v4 18/21] mm, THP, swap: Support PMD swap mapping in mincore() Huang, Ying
2018-06-22  3:51 ` [PATCH -mm -v4 19/21] mm, THP, swap: Support PMD swap mapping in common path Huang, Ying
2018-06-22  3:51 ` [PATCH -mm -v4 20/21] mm, THP, swap: create PMD swap mapping when unmap the THP Huang, Ying
2018-06-22  3:51 ` [PATCH -mm -v4 21/21] mm, THP: Avoid to split THP when reclaim MADV_FREE THP Huang, Ying
2018-06-28  4:51 ` [PATCH -mm -v4 00/21] mm, THP, swap: Swapout/swapin THP in one piece Andrew Morton
2018-06-28  5:29   ` Huang, Ying
2018-06-28  5:29     ` Huang, Ying
2018-06-28  5:31     ` Andrew Morton
2018-06-28  5:31       ` Andrew Morton
2018-06-28  5:35       ` Huang, Ying
2018-06-28  5:35         ` Huang, Ying
2018-06-28  6:18         ` Andrew Morton
2018-06-28  6:18           ` Andrew Morton
2018-06-28  9:03           ` Matthew Wilcox
2018-06-28  9:03             ` Matthew Wilcox
2018-06-29  1:17             ` Huang, Ying
2018-06-29  1:17               ` Huang, Ying
2018-06-29  5:57               ` Matthew Wilcox
2018-07-02  5:19                 ` Huang, Ying
2018-07-02  5:19                   ` Huang, Ying
2018-07-04  2:11   ` Sergey Senozhatsky
2018-07-04  2:20     ` Huang, Ying
2018-07-04  2:20       ` Huang, Ying
2018-07-04  2:27       ` Sergey Senozhatsky
2018-07-04  2:59         ` Huang, Ying
2018-07-04  2:59           ` Huang, Ying

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