lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <13f31dc5-cd0b-4120-af21-196619d8fa69@vivo.com>
Date:   Fri, 10 Nov 2023 09:51:02 +0800
From:   zhiguojiang <justinjiang@...o.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Johannes Weiner <hannes@...xchg.org>,
        opensource.kernel@...o.com
Subject: Re: [PATCH v2 1/1] mm: ALLOC_HIGHATOMIC flag allocation issue



在 2023/11/10 1:49, Andrew Morton 写道:
> On Thu,  9 Nov 2023 15:31:33 +0800 Zhiguo Jiang <justinjiang@...o.com> wrote:
>
>> Add a new bool* argument to pass return flag instead of *alloc_flags
>> and add the related comments.
> Please retain (and update) the changelog with each version of a patch.
ok,I will supplement it if there is a later version.
>
> For reviewers (please), here's the v1 changelog:
>
> : In case of alloc_flags contain ALLOC_HIGHATOMIC and alloc order
> : is order1/2/3/10 in rmqueue(), if pages are alloced successfully
> : from pcplist cache, and move a free pageblock from the alloced
> : migratetype freelist to MIGRATE_HIGHATOMIC freelist, rather than
> : alloc from MIGRATE_HIGHATOMIC freelist firstly, so this will result
> : in an increasing number of pages on the MIGRATE_HIGHATOMIC freelist,
> : pages in other migratetype freelist are reduced and more likely to
> : allocation failure.
> :
> : Currently the sequence of ALLOC_HIGHATOMIC allocation is:
> : pcplist cache --> buddy (batch >> order) allocation migratetype
> : freelist --> buddy MIGRATE_HIGHATOMIC freelist --> buddy allocation
> : migratetype freelist.
> :
> : Due to the fact that requesting pages from the pcplist cache is faster
> : than buddy, the sequence of modifying the ALLOC_HIGHATOMIC allocation is:
> : pcplist --> buddy MIGRATE_HIGHATOMIC freelist --> buddy allocation
> : migrate freelist.
> :
> : This patch can solve the allocation failure of the Non-ALLOC_HIGHATOMIC
> : alloc_flag due to excessive pages reservations in MIGRATE_HIGHATOMIC
> : freelists.
>
>> --- a/mm/internal.h
>> +++ b/mm/internal.h
>> @@ -905,7 +905,6 @@ unsigned int reclaim_clean_pages_from_list(struct zone *zone,
>>   #endif
>>   #define ALLOC_HIGHATOMIC	0x200 /* Allows access to MIGRATE_HIGHATOMIC */
>>   #define ALLOC_KSWAPD		0x800 /* allow waking of kswapd, __GFP_KSWAPD_RECLAIM set */
>> -#define ALLOC_PCPLIST		0x1000 /* Allocations from pcplist */
>>   
>>   /* Flags that allow allocations below the min watermark. */
>>   #define ALLOC_RESERVES (ALLOC_NON_BLOCK|ALLOC_MIN_RESERVE|ALLOC_HIGHATOMIC|ALLOC_OOM)
>> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
>> index 67cec88164b1..3c84c3e3eeb0 100755
>> --- a/mm/page_alloc.c
>> +++ b/mm/page_alloc.c
>> @@ -2854,6 +2854,11 @@ struct page *__rmqueue_pcplist(struct zone *zone, unsigned int order,
>>   			int batch = nr_pcp_alloc(pcp, zone, order);
>>   			int alloced;
>>   
>> +			/*
>> +			 * If pcplist is empty and alloc_flags is with ALLOC_HIGHATOMIC,
>> +			 * it should alloc from buddy highatomic migrate freelist firstly
>> +			 * to ensure quick and successful allocation.
>> +			 */
>>   			if (alloc_flags & ALLOC_HIGHATOMIC)
>>   				goto out;
>>   
>> @@ -2925,8 +2930,8 @@ __no_sanitize_memory
>>   static inline
>>   struct page *rmqueue(struct zone *preferred_zone,
>>   			struct zone *zone, unsigned int order,
>> -			gfp_t gfp_flags, unsigned int *alloc_flags,
>> -			int migratetype)
>> +			gfp_t gfp_flags, unsigned int alloc_flags,
>> +			int migratetype, bool *highatomc_allocation)
>>   {
>>   	struct page *page;
>>   
>> @@ -2938,19 +2943,33 @@ struct page *rmqueue(struct zone *preferred_zone,
>>   
>>   	if (likely(pcp_allowed_order(order))) {
>>   		page = rmqueue_pcplist(preferred_zone, zone, order,
>> -				       migratetype, *alloc_flags);
>> -		if (likely(page)) {
>> -			*alloc_flags |= ALLOC_PCPLIST;
>> +				       migratetype, alloc_flags);
>> +		if (likely(page))
>>   			goto out;
>> -		}
>>   	}
>>   
>> -	page = rmqueue_buddy(preferred_zone, zone, order, *alloc_flags,
>> +	page = rmqueue_buddy(preferred_zone, zone, order, alloc_flags,
>>   							migratetype);
>>   
>> +	/*
>> +	 * The high-order atomic allocation pageblock reserved conditions:
>> +	 *
>> +	 * If the high-order atomic allocation page is alloced from pcplist,
>> +	 * the highatomic pageblock does not need to be reserved, which can
>> +	 * void to migrate an increasing number of pages into buddy
>> +	 * MIGRATE_HIGHATOMIC freelist and lead to an increasing risk of
>> +	 * allocation failure on other buddy migrate freelists.
>> +	 *
>> +	 * If the high-order atomic allocation page is alloced from buddy
>> +	 * highatomic migrate freelist, regardless of whether the allocation
>> +	 * is successful or not, the highatomic pageblock can try to be
>> +	 * reserved.
>> +	 */
>> +	if (unlikely(alloc_flags & ALLOC_HIGHATOMIC))
>> +		*highatomc_allocation = true;
>>   out:
>>   	/* Separate test+clear to avoid unnecessary atomics */
>> -	if ((*alloc_flags & ALLOC_KSWAPD) &&
>> +	if ((alloc_flags & ALLOC_KSWAPD) &&
>>   	    unlikely(test_bit(ZONE_BOOSTED_WATERMARK, &zone->flags))) {
>>   		clear_bit(ZONE_BOOSTED_WATERMARK, &zone->flags);
>>   		wakeup_kswapd(zone, 0, 0, zone_idx(zone));
>> @@ -3218,6 +3237,7 @@ get_page_from_freelist(gfp_t gfp_mask, unsigned int order, int alloc_flags,
>>   	struct pglist_data *last_pgdat = NULL;
>>   	bool last_pgdat_dirty_ok = false;
>>   	bool no_fallback;
>> +	bool highatomc_allocation = false;
>>   
>>   retry:
>>   	/*
>> @@ -3349,7 +3369,7 @@ get_page_from_freelist(gfp_t gfp_mask, unsigned int order, int alloc_flags,
>>   
>>   try_this_zone:
>>   		page = rmqueue(ac->preferred_zoneref->zone, zone, order,
>> -				gfp_mask, &alloc_flags, ac->migratetype);
>> +				gfp_mask, alloc_flags, ac->migratetype, &highatomc_allocation);
>>   		if (page) {
>>   			prep_new_page(page, order, gfp_mask, alloc_flags);
>>   
>> @@ -3357,8 +3377,7 @@ get_page_from_freelist(gfp_t gfp_mask, unsigned int order, int alloc_flags,
>>   			 * If this is a high-order atomic allocation then check
>>   			 * if the pageblock should be reserved for the future
>>   			 */
>> -			if (unlikely(alloc_flags & ALLOC_HIGHATOMIC) &&
>> -				unlikely(!(alloc_flags & ALLOC_PCPLIST)))
>> +			if (unlikely(highatomc_allocation))
>>   				reserve_highatomic_pageblock(page, zone);
>>   
>>   			return page;
>> -- 
>> 2.39.0

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ