From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-173.mta0.migadu.com (out-173.mta0.migadu.com [91.218.175.173]) (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 9FED23ACA79 for ; Tue, 23 Jun 2026 07:57:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.173 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782201452; cv=none; b=vA0sJtpQMn2Nw0hCL9LIinqzqM2puwG9cImC9hnSx2OmMqgX5XRftA5FPoEhc/51JjPq5IebqguQLGdIC7N7xikGsxqAI/8vM/Wg6DORgOZ1w1iVzhVfO9JCtCfUUCRkHypBcSYT50U7RgeNFMwVjue9itDqdANx8o+HoBxngf4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782201452; c=relaxed/simple; bh=qLcUs4yU/ZR55hXqu3agXlKIB4llKDmF6rbrl+XmPBo=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=mCZCfwY4KPkENgETV29XT500LEb1OUp8pMkabV9yd9uW+eUQhiyBle7sB3Rju/Yjgz1U9p/JvVoYDoRfKO0ILssYBWWTHmvoayMa18eLHacn8mkLUJNh+nnhsU5nR+KfRF0ZsPRWXkAs26xs0ZUfAehNK0mQIbhp8/rZCIRL/+I= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=Z5WDdIhQ; arc=none smtp.client-ip=91.218.175.173 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="Z5WDdIhQ" Message-ID: <6e312b15-d2b5-4137-aa3f-720ec214c7ab@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1782201438; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=YOsWN24QMyB1OibJVwjOiiMJTHDGvvI4KR4pW3FCPv8=; b=Z5WDdIhQcPKYwsP7139hwnDvuxIFsJURgopt4k0Kk/bsCErWp1NK/K6Xlp62focm/inEn1 RHe2tkAe2wQP7kIEUxuzievOTEHmyxs+8JaJ6S+hOCm3cqGnW+7YQi+uoAAufTnR5Wlvyf hYHpWYv555v+dUIeT/roTWAEACAWYD4= Date: Tue, 23 Jun 2026 15:56:40 +0800 Precedence: bulk X-Mailing-List: linux-rt-devel@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH v2 13/13] mm: remove __GFP_NO_CODETAG To: Brendan Jackman , Vlastimil Babka Cc: "Harry Yoo (Oracle)" , Gregory Price , Alexei Starovoitov , Matthew Wilcox , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-rt-devel@lists.linux.dev, Michal Hocko , Andrew Morton , Johannes Weiner , Zi Yan , Muchun Song , Oscar Salvador , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Mike Rapoport , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Alistair Popple , Ying Huang , Hao Li , Christoph Lameter , David Rientjes , Roman Gushchin , Sebastian Andrzej Siewior , Clark Williams , Steven Rostedt , Suren Baghdasaryan References: <20260622-alloc-trylock-v2-0-31f31367d420@google.com> <20260622-alloc-trylock-v2-13-31f31367d420@google.com> Content-Language: en-US X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Hao Ge In-Reply-To: <20260622-alloc-trylock-v2-13-31f31367d420@google.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT Hi Brendan On 2026/6/22 18:01, Brendan Jackman wrote: > Now that alloc_pages has an entrypoint that allows passing alloc_flags, > we can take advantage of this to start removing GFP flags that are only > used for mm-internal stuff. > > This requires also plumbing the alloc_flags into some more of the > allocator code, in particular __alloc_pages[_noprof]() gets an > alloc_flags arg to go along with its callees, and we now need to pass > those flags deeper into the allocator so they can reach the alloc_tag > code. > > To try and keep the new ALLOC_NO_CODETAG's scope nice and narrow, don't > define it in mm/internal.h, instead just define a "reserved bit" and > then use that in places that don't care about what it means. > > Signed-off-by: Brendan Jackman Nit: The title says "remove __GFP_NO_CODETAG" but the flag isn't really removed — it's migrated from gfp_t to alloc_flags as ALLOC_NO_CODETAG. Something like "mm: replace __GFP_NO_CODETAG with an alloc_flag" would be more accurate. Additionally, as Lorenzo pointed out in another thread, you will likely need to rebase this series later. I noticed Vlastimil has already landed the slab changes removing __GFP_NO_OBJ_EXT into mainline: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=335c347686e76df9d2c7d7f61b5ea627a4c5cb4c For v3, it might make sense to fold in Vlastimil's patch so the full removal of __GFP_NO_OBJ_EXT can be completed end-to-end https://lore.kernel.org/all/20260609-slab_alloc_flags-v1-15-2bf4a4b9b526@kernel.org/ > --- > mm/alloc_tag.c | 18 ++++++++++-------- > mm/compaction.c | 4 ++-- > mm/internal.h | 8 ++++++-- > mm/page_alloc.c | 42 ++++++++++++++++++++++++------------------ > mm/page_frag_cache.c | 4 ++-- > 5 files changed, 44 insertions(+), 32 deletions(-) > > diff --git a/mm/alloc_tag.c b/mm/alloc_tag.c > index d9be1cf5187d9..61a6cba32ff35 100644 > --- a/mm/alloc_tag.c > +++ b/mm/alloc_tag.c > @@ -15,6 +15,8 @@ > #include > #include > > +#include "internal.h" > + > #define ALLOCINFO_FILE_NAME "allocinfo" > #define MODULE_ALLOC_TAG_VMAP_SIZE (100000UL * sizeof(struct alloc_tag)) > #define SECTION_START(NAME) (CODETAG_SECTION_START_PREFIX NAME) > @@ -785,16 +787,15 @@ struct pfn_pool { > sizeof(unsigned long)) > > /* > - * Skip early PFN recording for a page allocation. Reuses the > - * %__GFP_NO_OBJ_EXT bit. Used by __alloc_tag_add_early_pfn() to avoid > - * recursion when allocating pages for the early PFN tracking list > - * itself. > + * Skip early PFN recording for a page allocation. Used by > + * __alloc_tag_add_early_pfn() to avoid recursion when allocating pages for the > + * early PFN tracking list itself. > * > * Codetags of the pages allocated with __GFP_NO_CODETAG should be > * cleared (via clear_page_tag_ref()) before freeing the pages to prevent > * alloc_tag_sub_check() from triggering a warning. > */ > -#define __GFP_NO_CODETAG __GFP_NO_OBJ_EXT > +#define ALLOC_NO_CODETAG __ALLOC_ALLOC_TAG > > static struct pfn_pool *current_pfn_pool __initdata; > > @@ -806,7 +807,8 @@ static void __init __alloc_tag_add_early_pfn(unsigned long pfn) > do { > pool = READ_ONCE(current_pfn_pool); > if (!pool || atomic_read(&pool->count) >= PFN_POOL_SIZE) { > - struct page *new_page = alloc_page(__GFP_HIGH | __GFP_NO_CODETAG); > + struct page *new_page = __alloc_pages(__GFP_HIGH, 0, numa_mem_id(), > + NULL, ALLOC_NO_CODETAG); > struct pfn_pool *new; > > if (!new_page) { > @@ -837,7 +839,7 @@ typedef void alloc_tag_add_func(unsigned long pfn); > static alloc_tag_add_func __rcu *alloc_tag_add_early_pfn_ptr __refdata = > RCU_INITIALIZER(__alloc_tag_add_early_pfn); > > -void alloc_tag_add_early_pfn(unsigned long pfn, gfp_t gfp_flags) > +void alloc_tag_add_early_pfn(unsigned long pfn, unsigned int alloc_flags) alloc_tag_add_early_pfn is actually declared in include/linux/alloc_tag.h, so we need to update this header in sync as well. include/linux/alloc_tag.h:166:void alloc_tag_add_early_pfn(unsigned long pfn, gfp_t gfp_flags); include/linux/alloc_tag.h:170:static inline void alloc_tag_add_early_pfn(unsigned long pfn, gfp_t gfp_flags) {} > { > alloc_tag_add_func *alloc_tag_add; > > @@ -845,7 +847,7 @@ void alloc_tag_add_early_pfn(unsigned long pfn, gfp_t gfp_flags) > return; > > /* Skip allocations for the tracking list itself to avoid recursion. */ > - if (gfp_flags & __GFP_NO_CODETAG) > + if (alloc_flags & ALLOC_NO_CODETAG) > return; > > rcu_read_lock(); > diff --git a/mm/compaction.c b/mm/compaction.c > index b776f35ad0200..e90ebd2c54f48 100644 > --- a/mm/compaction.c > +++ b/mm/compaction.c > @@ -82,7 +82,7 @@ static inline bool is_via_compact_memory(int order) { return false; } > > static struct page *mark_allocated_noprof(struct page *page, unsigned int order, gfp_t gfp_flags) > { > - post_alloc_hook(page, order, __GFP_MOVABLE); > + post_alloc_hook(page, order, __GFP_MOVABLE, ALLOC_DEFAULT); > set_page_refcounted(page); > return page; > } > @@ -1850,7 +1850,7 @@ static struct folio *compaction_alloc_noprof(struct folio *src, unsigned long da > } > dst = (struct folio *)freepage; > > - post_alloc_hook(&dst->page, order, __GFP_MOVABLE); > + post_alloc_hook(&dst->page, order, __GFP_MOVABLE, ALLOC_DEFAULT); > set_page_refcounted(&dst->page); > if (order) > prep_compound_page(&dst->page, order); > diff --git a/mm/internal.h b/mm/internal.h > index 0847b55bfc147..a45bedb9ada5f 100644 > --- a/mm/internal.h > +++ b/mm/internal.h > @@ -684,6 +684,8 @@ struct alloc_context { > */ > enum zone_type highest_zoneidx; > bool spread_dirty_pages; > + /* Only flags that are global to the whole allocation go here. */ > + unsigned int alloc_flags; > }; > > /* > @@ -907,7 +909,8 @@ static inline void init_compound_tail(struct page *tail, > prep_compound_tail(tail, head, order); > } > > -void post_alloc_hook(struct page *page, unsigned int order, gfp_t gfp_flags); > +void post_alloc_hook(struct page *page, unsigned int order, gfp_t gfp_flags, > + unsigned int alloc_flags); > extern bool free_pages_prepare(struct page *page, unsigned int order); > > extern int user_min_free_kbytes; > @@ -1481,6 +1484,7 @@ unsigned int reclaim_clean_pages_from_list(struct zone *zone, > #define ALLOC_HIGHATOMIC 0x200 /* Allows access to MIGRATE_HIGHATOMIC */ > #define ALLOC_NOLOCK 0x400 /* Only use spin_trylock in allocation path */ > #define ALLOC_KSWAPD 0x800 /* allow waking of kswapd, __GFP_KSWAPD_RECLAIM set */ > +#define __ALLOC_ALLOC_TAG 0x1000 /* Reserved bit for use by alloc_tag code */ > > /* Flags that allow allocations below the min watermark. */ > #define ALLOC_RESERVES (ALLOC_NON_BLOCK|ALLOC_MIN_RESERVE|ALLOC_HIGHATOMIC|ALLOC_OOM) > @@ -1956,7 +1960,7 @@ bool may_expand_vm(struct mm_struct *mm, const vma_flags_t *vma_flags, > unsigned long npages); > > struct page *__alloc_pages_noprof(gfp_t gfp, unsigned int order, int preferred_nid, > - nodemask_t *nodemask); > + nodemask_t *nodemask, unsigned int alloc_flags); > #define __alloc_pages(...) alloc_hooks(__alloc_pages_noprof(__VA_ARGS__)) > > #endif /* __MM_INTERNAL_H */ > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index d99e4ea8307ea..d50fd9c77a2e8 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -1246,7 +1246,7 @@ void __clear_page_tag_ref(struct page *page) > /* Should be called only if mem_alloc_profiling_enabled() */ > static noinline > void __pgalloc_tag_add(struct page *page, struct task_struct *task, > - unsigned int nr, gfp_t gfp_flags) > + unsigned int nr, unsigned int alloc_flags) > { > union pgtag_ref_handle handle; > union codetag_ref ref; > @@ -1260,17 +1260,17 @@ void __pgalloc_tag_add(struct page *page, struct task_struct *task, > * page_ext is not available yet, record the pfn so we can > * clear the tag ref later when page_ext is initialized. > */ > - alloc_tag_add_early_pfn(page_to_pfn(page), gfp_flags); > + alloc_tag_add_early_pfn(page_to_pfn(page), alloc_flags); > if (task->alloc_tag) > alloc_tag_set_inaccurate(task->alloc_tag); > } > } > > static inline void pgalloc_tag_add(struct page *page, struct task_struct *task, > - unsigned int nr, gfp_t gfp_flags) > + unsigned int nr, unsigned int alloc_flags) The pgalloc_tag_add() stub in the non-CONFIG_MEM_ALLOC_PROFILING build could use the same parameter types for consistency Thanks Best Regards Hao > { > if (mem_alloc_profiling_enabled()) > - __pgalloc_tag_add(page, task, nr, gfp_flags); > + __pgalloc_tag_add(page, task, nr, alloc_flags); > } > > /* Should be called only if mem_alloc_profiling_enabled() */ > @@ -1807,7 +1807,7 @@ static inline bool should_skip_init(gfp_t flags) > } > > inline void post_alloc_hook(struct page *page, unsigned int order, > - gfp_t gfp_flags) > + gfp_t gfp_flags, unsigned int alloc_flags) > { > const bool zero_tags = gfp_flags & __GFP_ZEROTAGS; > bool init = !want_init_on_free() && want_init_on_alloc(gfp_flags) && > @@ -1858,13 +1858,13 @@ inline void post_alloc_hook(struct page *page, unsigned int order, > > set_page_owner(page, order, gfp_flags); > page_table_check_alloc(page, order); > - pgalloc_tag_add(page, current, 1 << order, gfp_flags); > + pgalloc_tag_add(page, current, 1 << order, alloc_flags); > } > > static void prep_new_page(struct page *page, unsigned int order, gfp_t gfp_flags, > unsigned int alloc_flags) > { > - post_alloc_hook(page, order, gfp_flags); > + post_alloc_hook(page, order, gfp_flags, alloc_flags); > > if (order && (gfp_flags & __GFP_COMP)) > prep_compound_page(page, order); > @@ -4773,8 +4773,12 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, > * The fast path uses conservative alloc_flags to succeed only until > * kswapd needs to be woken up, and to avoid the cost of setting up > * alloc_flags precisely. So we do that now. > + * > + * Can't just or alloc_flags if it contains WMARK bits, but those flags > + * shouldn't be set in ac->alloc_flags. > */ > - alloc_flags = slowpath_alloc_flags(gfp_mask, order); > + VM_WARN_ON(ac->alloc_flags & ALLOC_WMARK_MASK); > + alloc_flags = ac->alloc_flags | slowpath_alloc_flags(gfp_mask, order); > > /* > * We need to recalculate the starting point for the zonelist iterator > @@ -4816,7 +4820,7 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, > reserve_flags = __gfp_pfmemalloc_flags(gfp_mask); > if (reserve_flags) > alloc_flags = cma_alloc_flags(gfp_mask, reserve_flags) | > - (alloc_flags & ALLOC_KSWAPD); > + ac->alloc_flags | (alloc_flags & ALLOC_KSWAPD); > > /* > * Reset the nodemask and zonelist iterators if memory policies can be > @@ -5218,7 +5222,7 @@ unsigned long alloc_pages_bulk_noprof(gfp_t gfp, int preferred_nid, > return nr_populated; > > failed: > - page = __alloc_pages_noprof(gfp, 0, preferred_nid, nodemask); > + page = __alloc_pages_noprof(gfp, 0, preferred_nid, nodemask, ALLOC_DEFAULT); > if (page) > page_array[nr_populated++] = page; > goto out; > @@ -5326,11 +5330,13 @@ struct page *__alloc_frozen_pages_noprof(gfp_t gfp, unsigned int order, > { > struct page *page; > gfp_t alloc_gfp; /* The gfp_t that was actually used for allocation */ > - struct alloc_context ac = { }; > + struct alloc_context ac = { > + .alloc_flags = alloc_flags, > + }; > unsigned int fastpath_alloc_flags = alloc_flags; > > /* Other flags could be supported later if needed. */ > - if (WARN_ON(alloc_flags & ~ALLOC_NOLOCK)) > + if (WARN_ON(alloc_flags & ~(ALLOC_NOLOCK | __ALLOC_ALLOC_TAG))) > return NULL; > > if (!alloc_order_allowed(gfp, order, alloc_flags)) > @@ -5398,12 +5404,12 @@ struct page *__alloc_frozen_pages_noprof(gfp_t gfp, unsigned int order, > EXPORT_SYMBOL(__alloc_frozen_pages_noprof); > > struct page *__alloc_pages_noprof(gfp_t gfp, unsigned int order, > - int preferred_nid, nodemask_t *nodemask) > + int preferred_nid, nodemask_t *nodemask, unsigned int alloc_flags) > { > struct page *page; > > page = __alloc_frozen_pages_noprof(gfp, order, preferred_nid, nodemask, > - ALLOC_DEFAULT); > + alloc_flags); > if (page) > set_page_refcounted(page); > return page; > @@ -5418,14 +5424,14 @@ struct page *alloc_pages_node_noprof(int nid, gfp_t gfp_mask, unsigned int order > VM_BUG_ON(nid < 0 || nid >= MAX_NUMNODES); > warn_if_node_offline(nid, gfp_mask); > > - return __alloc_pages_noprof(gfp_mask, order, nid, NULL); > + return __alloc_pages_noprof(gfp_mask, order, nid, NULL, ALLOC_DEFAULT); > } > > struct folio *__folio_alloc_noprof(gfp_t gfp, unsigned int order, int preferred_nid, > nodemask_t *nodemask) > { > struct page *page = __alloc_pages_noprof(gfp | __GFP_COMP, order, > - preferred_nid, nodemask); > + preferred_nid, nodemask, ALLOC_DEFAULT); > return page_rmappable_folio(page); > } > EXPORT_SYMBOL(__folio_alloc_noprof); > @@ -7107,7 +7113,7 @@ static void split_free_frozen_pages(struct list_head *list, gfp_t gfp_mask) > list_for_each_entry_safe(page, next, &list[order], lru) { > int i; > > - post_alloc_hook(page, order, gfp_mask); > + post_alloc_hook(page, order, gfp_mask, ALLOC_DEFAULT); > if (!order) > continue; > > @@ -7312,7 +7318,7 @@ int alloc_contig_frozen_range_noprof(unsigned long start, unsigned long end, > struct page *head = pfn_to_page(start); > > check_new_pages(head, order); > - prep_new_page(head, order, gfp_mask, 0); > + prep_new_page(head, order, gfp_mask, ALLOC_DEFAULT); > } else { > ret = -EINVAL; > WARN(true, "PFN range: requested [%lu, %lu), allocated [%lu, %lu)\n", > diff --git a/mm/page_frag_cache.c b/mm/page_frag_cache.c > index d2423f30577e4..d9573170e0719 100644 > --- a/mm/page_frag_cache.c > +++ b/mm/page_frag_cache.c > @@ -57,10 +57,10 @@ static struct page *__page_frag_cache_refill(struct page_frag_cache *nc, > gfp_mask = (gfp_mask & ~__GFP_DIRECT_RECLAIM) | __GFP_COMP | > __GFP_NOWARN | __GFP_NORETRY | __GFP_NOMEMALLOC; > page = __alloc_pages(gfp_mask, PAGE_FRAG_CACHE_MAX_ORDER, > - numa_mem_id(), NULL); > + numa_mem_id(), NULL, ALLOC_DEFAULT); > #endif > if (unlikely(!page)) { > - page = __alloc_pages(gfp, 0, numa_mem_id(), NULL); > + page = __alloc_pages(gfp, 0, numa_mem_id(), NULL, ALLOC_DEFAULT); > order = 0; > } > >