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From: Oscar Salvador <osalvador@suse.de>
To: Muchun Song <songmuchun@bytedance.com>
Cc: corbet@lwn.net, mike.kravetz@oracle.com, tglx@linutronix.de,
	mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com,
	dave.hansen@linux.intel.com, luto@kernel.org,
	peterz@infradead.org, viro@zeniv.linux.org.uk,
	akpm@linux-foundation.org, paulmck@kernel.org,
	mchehab+huawei@kernel.org, pawan.kumar.gupta@linux.intel.com,
	rdunlap@infradead.org, oneukum@suse.com,
	anshuman.khandual@arm.com, jroedel@suse.de,
	almasrymina@google.com, rientjes@google.com, willy@infradead.org,
	mhocko@suse.com, song.bao.hua@hisilicon.com, david@redhat.com,
	naoya.horiguchi@nec.com, duanxiongchun@bytedance.com,
	linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH v10 10/11] mm/hugetlb: Gather discrete indexes of tail page
Date: Fri, 18 Dec 2020 10:06:31 +0100	[thread overview]
Message-ID: <20201218090631.GA3623@localhost.localdomain> (raw)
In-Reply-To: <20201217121303.13386-11-songmuchun@bytedance.com>

On Thu, Dec 17, 2020 at 08:13:02PM +0800, Muchun Song wrote:
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 6c02f49959fd..78dd88dda857 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -1360,7 +1360,7 @@ static inline void hwpoison_subpage_deliver(struct hstate *h, struct page *head)
>  	if (!PageHWPoison(head) || !free_vmemmap_pages_per_hpage(h))
>  		return;
>  
> -	page = head + page_private(head + 4);
> +	page = head + page_private(head + SUBPAGE_INDEX_HWPOISON);
>  
>  	/*
>  	 * Move PageHWPoison flag from head page to the raw error page,
> @@ -1379,7 +1379,7 @@ static inline void hwpoison_subpage_set(struct hstate *h, struct page *head,
>  		return;
>  
>  	if (free_vmemmap_pages_per_hpage(h)) {
> -		set_page_private(head + 4, page - head);
> +		set_page_private(head + SUBPAGE_INDEX_HWPOISON, page - head);

Ok, I was too eager here.

If CONFIG_HUGETLB_PAGE_FREE_VMEMMAP is not set for whatever reason
(e.g: CONFIG_MEMORY_HOTREMOVE is disabled), when you convert "+4"
to its index (SUBPAGE_INDEX_HWPOISON), this will no longer build
since we only define SUBPAGE_INDEX_HWPOISON when the config
option CONFIG_HUGETLB_PAGE_FREE_VMEMMAP is set.

Different things can be done to fix this:

e.g:

 - Define a two different hwpoison_subpage_{deliver,set}
   and have them under
   #ifdef CONFIG_HUGETLB_PAGE_FREE_VMEMMAP
   ...
   #else
   ...
   #endif

 - Work it around as is with IS_ENABLED(CONFIG_HUGETLB_...
 - Have a common entry and decide depending on whether
   the config is enabled.

I guess option #1 might be cleaner.

-- 
Oscar Salvador
SUSE L3

  reply	other threads:[~2020-12-18  9:07 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-17 12:12 [PATCH v10 00/11] Free some vmemmap pages of HugeTLB page Muchun Song
2020-12-17 12:12 ` [PATCH v10 01/11] mm/memory_hotplug: Factor out bootmem core functions to bootmem_info.c Muchun Song
2020-12-17 12:12 ` [PATCH v10 02/11] mm/hugetlb: Introduce a new config HUGETLB_PAGE_FREE_VMEMMAP Muchun Song
2020-12-18 15:41   ` Oscar Salvador
2020-12-21 23:56   ` Mike Kravetz
2020-12-17 12:12 ` [PATCH v10 03/11] mm/hugetlb: Free the vmemmap pages associated with each HugeTLB page Muchun Song
2020-12-21  9:11   ` Oscar Salvador
2020-12-21 11:25     ` [External] " Muchun Song
2020-12-21 13:43       ` Oscar Salvador
2020-12-21 15:52         ` Muchun Song
2020-12-21 18:00           ` Oscar Salvador
2020-12-22  1:03             ` Mike Kravetz
2020-12-22  2:49             ` Muchun Song
2020-12-17 12:12 ` [PATCH v10 04/11] mm/hugetlb: Defer freeing of HugeTLB pages Muchun Song
2020-12-21 10:27   ` Oscar Salvador
2020-12-21 11:07     ` [External] " Muchun Song
2020-12-21 14:14       ` Oscar Salvador
2020-12-21 15:18         ` Muchun Song
2020-12-17 12:12 ` [PATCH v10 05/11] mm/hugetlb: Allocate the vmemmap pages associated with each HugeTLB page Muchun Song
2020-12-17 12:12 ` [PATCH v10 06/11] mm/hugetlb: Set the PageHWPoison to the raw error page Muchun Song
2020-12-17 12:12 ` [PATCH v10 07/11] mm/hugetlb: Flush work when dissolving hugetlb page Muchun Song
2020-12-21 10:40   ` Oscar Salvador
2020-12-21 11:07     ` [External] " Muchun Song
2020-12-17 12:13 ` [PATCH v10 08/11] mm/hugetlb: Add a kernel parameter hugetlb_free_vmemmap Muchun Song
2020-12-17 12:13 ` [PATCH v10 09/11] mm/hugetlb: Introduce nr_free_vmemmap_pages in the struct hstate Muchun Song
2020-12-21  8:16   ` Oscar Salvador
2020-12-21  9:33     ` [External] " Muchun Song
2020-12-17 12:13 ` [PATCH v10 10/11] mm/hugetlb: Gather discrete indexes of tail page Muchun Song
2020-12-18  9:06   ` Oscar Salvador [this message]
2020-12-18  9:41     ` [External] " Muchun Song
2020-12-17 12:13 ` [PATCH v10 11/11] mm/hugetlb: Optimize the code with the help of the compiler Muchun Song
2020-12-17 12:17 ` [PATCH v10 00/11] Free some vmemmap pages of HugeTLB page David Hildenbrand
2020-12-17 14:59 ` Oscar Salvador
2020-12-17 15:52   ` [External] " Muchun Song

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