From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C21C71BE223; Tue, 2 Jul 2024 17:16:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719940596; cv=none; b=f+d99/lGgtzPmNtdvVpU6+comqoKpFTljl1Dd8mpPqhP3VIuKHr75gIFh4QWjY2tOlqXfBnWQDlapyZ/2hp9p4wUKPbe4R4KGkTRXP8GGMT3UnU0bTvKBp574Vj9MyE7sA7z1kJVfCtB0p6ztNP9y6prq2/O1UZJrsL2582Lk7I= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719940596; c=relaxed/simple; bh=IyA/ubz4lxv8kiYGpVVLYhCndhyapOZNaQ9m78NV7Rw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=t1fo2cLK+b+ZCwzwBm6P+Gcc5cep833zosecZYITaKmR6yCFCprAgnQwqZKoqMYT9IKwtg5ClLhszJJ3Vs+hA+u75DXoK2xZzlkMHiMbHj9cQHkulX7FP+MDIeIR+fhSwebbKE/S08Ml6GvfYjZLFnocfNWhKegjpD6s1mGYkt0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=dxhOugz5; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="dxhOugz5" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 48AEDC116B1; Tue, 2 Jul 2024 17:16:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1719940596; bh=IyA/ubz4lxv8kiYGpVVLYhCndhyapOZNaQ9m78NV7Rw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=dxhOugz5JLDBF20tQvp5brmtDXJtiMMtHWj62kFu1lpN9M3vaGgEfRsbI95jbU4CY B7OhE5GNM7exYyJMrRUhuSvSqld1hUsb3MAhhw34ua7RjR3HBRT82K/XJXRyJ5K7Ls k3QReWQAEslWgPl/SGDF3aZoH7rDObiNm+sWeevU= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, yangge , Baolin Wang , Barry Song <21cnbao@gmail.com>, Mel Gorman , Andrew Morton Subject: [PATCH 6.9 202/222] mm/page_alloc: Separate THP PCP into movable and non-movable categories Date: Tue, 2 Jul 2024 19:04:00 +0200 Message-ID: <20240702170251.706841578@linuxfoundation.org> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20240702170243.963426416@linuxfoundation.org> References: <20240702170243.963426416@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: yangge commit bf14ed81f571f8dba31cd72ab2e50fbcc877cc31 upstream. Since commit 5d0a661d808f ("mm/page_alloc: use only one PCP list for THP-sized allocations") no longer differentiates the migration type of pages in THP-sized PCP list, it's possible that non-movable allocation requests may get a CMA page from the list, in some cases, it's not acceptable. If a large number of CMA memory are configured in system (for example, the CMA memory accounts for 50% of the system memory), starting a virtual machine with device passthrough will get stuck. During starting the virtual machine, it will call pin_user_pages_remote(..., FOLL_LONGTERM, ...) to pin memory. Normally if a page is present and in CMA area, pin_user_pages_remote() will migrate the page from CMA area to non-CMA area because of FOLL_LONGTERM flag. But if non-movable allocation requests return CMA memory, migrate_longterm_unpinnable_pages() will migrate a CMA page to another CMA page, which will fail to pass the check in check_and_migrate_movable_pages() and cause migration endless. Call trace: pin_user_pages_remote --__gup_longterm_locked // endless loops in this function ----_get_user_pages_locked ----check_and_migrate_movable_pages ------migrate_longterm_unpinnable_pages --------alloc_migration_target This problem will also have a negative impact on CMA itself. For example, when CMA is borrowed by THP, and we need to reclaim it through cma_alloc() or dma_alloc_coherent(), we must move those pages out to ensure CMA's users can retrieve that contigous memory. Currently, CMA's memory is occupied by non-movable pages, meaning we can't relocate them. As a result, cma_alloc() is more likely to fail. To fix the problem above, we add one PCP list for THP, which will not introduce a new cacheline for struct per_cpu_pages. THP will have 2 PCP lists, one PCP list is used by MOVABLE allocation, and the other PCP list is used by UNMOVABLE allocation. MOVABLE allocation contains GPF_MOVABLE, and UNMOVABLE allocation contains GFP_UNMOVABLE and GFP_RECLAIMABLE. Link: https://lkml.kernel.org/r/1718845190-4456-1-git-send-email-yangge1116@126.com Fixes: 5d0a661d808f ("mm/page_alloc: use only one PCP list for THP-sized allocations") Signed-off-by: yangge Cc: Baolin Wang Cc: Barry Song <21cnbao@gmail.com> Cc: Mel Gorman Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman --- include/linux/mmzone.h | 9 ++++----- mm/page_alloc.c | 9 +++++++-- 2 files changed, 11 insertions(+), 7 deletions(-) --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -651,13 +651,12 @@ enum zone_watermarks { }; /* - * One per migratetype for each PAGE_ALLOC_COSTLY_ORDER. One additional list - * for THP which will usually be GFP_MOVABLE. Even if it is another type, - * it should not contribute to serious fragmentation causing THP allocation - * failures. + * One per migratetype for each PAGE_ALLOC_COSTLY_ORDER. Two additional lists + * are added for THP. One PCP list is used by GPF_MOVABLE, and the other PCP list + * is used by GFP_UNMOVABLE and GFP_RECLAIMABLE. */ #ifdef CONFIG_TRANSPARENT_HUGEPAGE -#define NR_PCP_THP 1 +#define NR_PCP_THP 2 #else #define NR_PCP_THP 0 #endif --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -521,10 +521,15 @@ out: static inline unsigned int order_to_pindex(int migratetype, int order) { + bool __maybe_unused movable; + #ifdef CONFIG_TRANSPARENT_HUGEPAGE if (order > PAGE_ALLOC_COSTLY_ORDER) { VM_BUG_ON(order != pageblock_order); - return NR_LOWORDER_PCP_LISTS; + + movable = migratetype == MIGRATE_MOVABLE; + + return NR_LOWORDER_PCP_LISTS + movable; } #else VM_BUG_ON(order > PAGE_ALLOC_COSTLY_ORDER); @@ -538,7 +543,7 @@ static inline int pindex_to_order(unsign int order = pindex / MIGRATE_PCPTYPES; #ifdef CONFIG_TRANSPARENT_HUGEPAGE - if (pindex == NR_LOWORDER_PCP_LISTS) + if (pindex >= NR_LOWORDER_PCP_LISTS) order = pageblock_order; #else VM_BUG_ON(order > PAGE_ALLOC_COSTLY_ORDER);