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 1D5501C9B9B; Mon, 16 Dec 2024 16:57:30 +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=1734368251; cv=none; b=GXZT5+rLhjx10Aaag4ae+cNMGd60ixrkRhP+ckLWQ4yriiXSsPd9/M1AoFCsqAbNPP2MxSNHrfSTvq2tl061rG74qmPdtBMs2AK2KWV+gFBKZupCzfUfx71UjH9oAnyIMhY3zVNVA3W0hueTNs383qeeO2bKy8OEIMziTjkL2Eg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734368251; c=relaxed/simple; bh=rHVRkW2GHn2zDA48jsGrXdtqGkdG8/EWEMV2UC6pN4M=; h=Date:To:From:Subject:Message-Id; b=FR8Yv8yemB2dM9PA6i8fQZK2fYYEMHbPuT7bdg1eamYsfnVRDlSXHbs7czu8XitALYFdAhW1/cjrcugbDbipSnaUp3bzq3xhVBAsS6TTmyBo1sQ5fQEH7mUlRXB6yd3F1Nj1VCaxHLYeKiDvgP88o6bN3/aZZfT1YTZRSJIIVX4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=uniQaLX2; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="uniQaLX2" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 97162C4CED0; Mon, 16 Dec 2024 16:57:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1734368250; bh=rHVRkW2GHn2zDA48jsGrXdtqGkdG8/EWEMV2UC6pN4M=; h=Date:To:From:Subject:From; b=uniQaLX2NquGqwpctb6DU0l32YU5XNx6QaIi6+PTqWWWozc9HwTfpCAOHHOzJehXK 2sjbHI031qNchU1w0TmH1UyBfiU4tmTNJXRAH6kNYwl+kJH13yvjvDpMfJp6uYaMm9 8IkY5X0aPWGFArf9qAS99w2KfQ35Tm1fpFYnUpnA= Date: Mon, 16 Dec 2024 08:57:30 -0800 To: mm-commits@vger.kernel.org,vbabka@suse.cz,stable@vger.kernel.org,david@redhat.com,baolin.wang@linux.alibaba.com,yangge1116@126.com,akpm@linux-foundation.org From: Andrew Morton Subject: + mm-compaction-dont-use-alloc_cma-in-long-term-gup-flow.patch added to mm-hotfixes-unstable branch Message-Id: <20241216165730.97162C4CED0@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: mm, compaction: don't use ALLOC_CMA in long term GUP flow has been added to the -mm mm-hotfixes-unstable branch. Its filename is mm-compaction-dont-use-alloc_cma-in-long-term-gup-flow.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-compaction-dont-use-alloc_cma-in-long-term-gup-flow.patch This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: yangge Subject: mm, compaction: don't use ALLOC_CMA in long term GUP flow Date: Mon, 16 Dec 2024 19:54:04 +0800 Since commit 984fdba6a32e ("mm, compaction: use proper alloc_flags in __compaction_suitable()") allow compaction to proceed when free pages required for compaction reside in the CMA pageblocks, it's possible that __compaction_suitable() always returns true, and in some cases, it's not acceptable. There are 4 NUMA nodes on my machine, and each NUMA node has 32GB of memory. I have configured 16GB of CMA memory on each NUMA node, and starting a 32GB virtual machine with device passthrough is extremely slow, taking almost an hour. During the start-up of the virtual machine, it will call pin_user_pages_remote(..., FOLL_LONGTERM, ...) to allocate memory. Long term GUP cannot allocate memory from CMA area, so a maximum of 16 GB of no-CMA memory on a NUMA node can be used as virtual machine memory. Since there is 16G of free CMA memory on the NUMA node, watermark for order-0 always be met for compaction, so __compaction_suitable() always returns true, even if the node is unable to allocate non-CMA memory for the virtual machine. For costly allocations, because __compaction_suitable() always returns true, __alloc_pages_slowpath() can't exit at the appropriate place, resulting in excessively long virtual machine startup times. Call trace: __alloc_pages_slowpath if (compact_result == COMPACT_SKIPPED || compact_result == COMPACT_DEFERRED) goto nopage; // should exit __alloc_pages_slowpath() from here In order to quickly fall back to remote node, we should remove ALLOC_CMA both in __compaction_suitable() and __isolate_free_page() in long term GUP flow. After this fix, starting a 32GB virtual machine with device passthrough takes only a few seconds. Link: https://lkml.kernel.org/r/1734350044-12928-1-git-send-email-yangge1116@126.com Fixes: 984fdba6a32e ("mm, compaction: use proper alloc_flags in __compaction_suitable()") Signed-off-by: yangge Cc: Baolin Wang Cc: David Hildenbrand Cc: Vlastimil Babka Cc: Signed-off-by: Andrew Morton --- include/linux/compaction.h | 6 ++++-- mm/compaction.c | 20 +++++++++++--------- mm/internal.h | 3 ++- mm/page_alloc.c | 6 ++++-- mm/page_isolation.c | 3 ++- mm/page_reporting.c | 2 +- mm/vmscan.c | 4 ++-- 7 files changed, 26 insertions(+), 18 deletions(-) --- a/include/linux/compaction.h~mm-compaction-dont-use-alloc_cma-in-long-term-gup-flow +++ a/include/linux/compaction.h @@ -90,7 +90,8 @@ extern enum compact_result try_to_compac struct page **page); extern void reset_isolation_suitable(pg_data_t *pgdat); extern bool compaction_suitable(struct zone *zone, int order, - int highest_zoneidx); + int highest_zoneidx, + unsigned int alloc_flags); extern void compaction_defer_reset(struct zone *zone, int order, bool alloc_success); @@ -108,7 +109,8 @@ static inline void reset_isolation_suita } static inline bool compaction_suitable(struct zone *zone, int order, - int highest_zoneidx) + int highest_zoneidx, + unsigned int alloc_flags) { return false; } --- a/mm/compaction.c~mm-compaction-dont-use-alloc_cma-in-long-term-gup-flow +++ a/mm/compaction.c @@ -654,7 +654,7 @@ static unsigned long isolate_freepages_b /* Found a free page, will break it into order-0 pages */ order = buddy_order(page); - isolated = __isolate_free_page(page, order); + isolated = __isolate_free_page(page, order, cc->alloc_flags); if (!isolated) break; set_page_private(page, order); @@ -1633,7 +1633,7 @@ static void fast_isolate_freepages(struc /* Isolate the page if available */ if (page) { - if (__isolate_free_page(page, order)) { + if (__isolate_free_page(page, order, cc->alloc_flags)) { set_page_private(page, order); nr_isolated = 1 << order; nr_scanned += nr_isolated - 1; @@ -2379,6 +2379,7 @@ static enum compact_result compact_finis static bool __compaction_suitable(struct zone *zone, int order, int highest_zoneidx, + unsigned int alloc_flags, unsigned long wmark_target) { unsigned long watermark; @@ -2393,25 +2394,26 @@ static bool __compaction_suitable(struct * even if compaction succeeds. * For costly orders, we require low watermark instead of min for * compaction to proceed to increase its chances. - * ALLOC_CMA is used, as pages in CMA pageblocks are considered - * suitable migration targets + * In addition to long term GUP flow, ALLOC_CMA is used, as pages in + * CMA pageblocks are considered suitable migration targets */ watermark = (order > PAGE_ALLOC_COSTLY_ORDER) ? low_wmark_pages(zone) : min_wmark_pages(zone); watermark += compact_gap(order); return __zone_watermark_ok(zone, 0, watermark, highest_zoneidx, - ALLOC_CMA, wmark_target); + alloc_flags & ALLOC_CMA, wmark_target); } /* * compaction_suitable: Is this suitable to run compaction on this zone now? */ -bool compaction_suitable(struct zone *zone, int order, int highest_zoneidx) +bool compaction_suitable(struct zone *zone, int order, int highest_zoneidx, + unsigned int alloc_flags) { enum compact_result compact_result; bool suitable; - suitable = __compaction_suitable(zone, order, highest_zoneidx, + suitable = __compaction_suitable(zone, order, highest_zoneidx, alloc_flags, zone_page_state(zone, NR_FREE_PAGES)); /* * fragmentation index determines if allocation failures are due to @@ -2472,7 +2474,7 @@ bool compaction_zonelist_suitable(struct available = zone_reclaimable_pages(zone) / order; available += zone_page_state_snapshot(zone, NR_FREE_PAGES); if (__compaction_suitable(zone, order, ac->highest_zoneidx, - available)) + alloc_flags, available)) return true; } @@ -2497,7 +2499,7 @@ compaction_suit_allocation_order(struct alloc_flags)) return COMPACT_SUCCESS; - if (!compaction_suitable(zone, order, highest_zoneidx)) + if (!compaction_suitable(zone, order, highest_zoneidx, alloc_flags)) return COMPACT_SKIPPED; return COMPACT_CONTINUE; --- a/mm/internal.h~mm-compaction-dont-use-alloc_cma-in-long-term-gup-flow +++ a/mm/internal.h @@ -662,7 +662,8 @@ static inline void clear_zone_contiguous zone->contiguous = false; } -extern int __isolate_free_page(struct page *page, unsigned int order); +extern int __isolate_free_page(struct page *page, unsigned int order, + unsigned int alloc_flags); extern void __putback_isolated_page(struct page *page, unsigned int order, int mt); extern void memblock_free_pages(struct page *page, unsigned long pfn, --- a/mm/page_alloc.c~mm-compaction-dont-use-alloc_cma-in-long-term-gup-flow +++ a/mm/page_alloc.c @@ -2808,7 +2808,8 @@ void split_page(struct page *page, unsig } EXPORT_SYMBOL_GPL(split_page); -int __isolate_free_page(struct page *page, unsigned int order) +int __isolate_free_page(struct page *page, unsigned int order, + unsigned int alloc_flags) { struct zone *zone = page_zone(page); int mt = get_pageblock_migratetype(page); @@ -2822,7 +2823,8 @@ int __isolate_free_page(struct page *pag * exists. */ watermark = zone->_watermark[WMARK_MIN] + (1UL << order); - if (!zone_watermark_ok(zone, 0, watermark, 0, ALLOC_CMA)) + if (!zone_watermark_ok(zone, 0, watermark, 0, + alloc_flags & ALLOC_CMA)) return 0; } --- a/mm/page_isolation.c~mm-compaction-dont-use-alloc_cma-in-long-term-gup-flow +++ a/mm/page_isolation.c @@ -229,7 +229,8 @@ static void unset_migratetype_isolate(st buddy = find_buddy_page_pfn(page, page_to_pfn(page), order, NULL); if (buddy && !is_migrate_isolate_page(buddy)) { - isolated_page = !!__isolate_free_page(page, order); + isolated_page = !!__isolate_free_page(page, order, + ALLOC_CMA); /* * Isolating a free page in an isolated pageblock * is expected to always work as watermarks don't --- a/mm/page_reporting.c~mm-compaction-dont-use-alloc_cma-in-long-term-gup-flow +++ a/mm/page_reporting.c @@ -198,7 +198,7 @@ page_reporting_cycle(struct page_reporti /* Attempt to pull page from list and place in scatterlist */ if (*offset) { - if (!__isolate_free_page(page, order)) { + if (!__isolate_free_page(page, order, ALLOC_CMA)) { next = page; break; } --- a/mm/vmscan.c~mm-compaction-dont-use-alloc_cma-in-long-term-gup-flow +++ a/mm/vmscan.c @@ -5861,7 +5861,7 @@ static inline bool should_continue_recla sc->reclaim_idx, 0)) return false; - if (compaction_suitable(zone, sc->order, sc->reclaim_idx)) + if (compaction_suitable(zone, sc->order, sc->reclaim_idx, ALLOC_CMA)) return false; } @@ -6089,7 +6089,7 @@ static inline bool compaction_ready(stru return true; /* Compaction cannot yet proceed. Do reclaim. */ - if (!compaction_suitable(zone, sc->order, sc->reclaim_idx)) + if (!compaction_suitable(zone, sc->order, sc->reclaim_idx, ALLOC_CMA)) return false; /* _ Patches currently in -mm which might be from yangge1116@126.com are mm-compaction-dont-use-alloc_cma-in-long-term-gup-flow.patch