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[80.230.25.21]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-488fc17f642sm364997035e9.5.2026.04.21.15.02.00 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 21 Apr 2026 15:02:02 -0700 (PDT) Date: Tue, 21 Apr 2026 18:01:59 -0400 From: "Michael S. Tsirkin" To: linux-kernel@vger.kernel.org Cc: Andrew Morton , David Hildenbrand , Vlastimil Babka , Brendan Jackman , Michal Hocko , Suren Baghdasaryan , Jason Wang , Andrea Arcangeli , Gregory Price , linux-mm@kvack.org, virtualization@lists.linux.dev, Johannes Weiner , Zi Yan , Lorenzo Stoakes , "Liam R. Howlett" , Mike Rapoport Subject: [PATCH RFC v3 15/19] mm: add free_frozen_pages_zeroed Message-ID: <86755bb7ab63e2374a242ce24a9a3f1981f10583.1776808210.git.mst@redhat.com> References: MIME-Version: 1.0 In-Reply-To: X-Mailer: git-send-email 2.27.0.106.g8ac3dc51b1 X-Mutt-Fcc: =sent X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: 7mPQ7Wdq59uNS6w_HZVWrFvVXkXKL3KIMmtnRfWZ6kQ_1776808924 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline X-Stat-Signature: j9rhwdgnk63cxy58ezxrx9r6mprq44gy X-Rspam-User: X-Rspamd-Queue-Id: 0B71E40010 X-Rspamd-Server: rspam05 X-HE-Tag: 1776808926-568098 X-HE-Meta: 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 ujtw1JRV wzM6cfvs6V8AQeDsDOSZteG5Ua3IAwP2EsGJHmSBIj2uk0UcxUYOrqZmMl5Ku1/DuEVsMg2Y55Pm9FgPd0Cvx+RkImqJEdr1P9rK9RE8xeSxCQF5aslVuv6lMpzE+k+mdu6lLcnS6jICMgicQi4bWxSwEuUGIWukuCi5aEa0/avY4LxQzwd5ID6Wj1eCiC7X+6DKkiPgPOh+2YnUOFGfnjBZBx27Mq1cVkG6W4sQMwTK6QOMKt1JIl0Eb5OjjlOZmg2Xgr5lXimeytB4n05VmiyCgpvLzq1FoaSanc/dVuxGoBSindb1dxp3Gba5lcbF6wGWkK8p0VAsWZdOwUhSEOxDMvqqAOfnSeCVgFzKkVWaCf+xys6kytGUPVA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Add free_frozen_pages_zeroed(page, order) to free a frozen page while marking it as zeroed, so the next allocation can skip redundant zeroing. An FPI_ZEROED internal flag carries the hint through the free path. PageZeroed is set after __free_pages_prepare() clears all flags, so the hint survives on the free list. Signed-off-by: Michael S. Tsirkin Assisted-by: Claude:claude-opus-4-6 --- include/linux/gfp.h | 1 + mm/internal.h | 1 - mm/page_alloc.c | 21 ++++++++++++++++++++- 3 files changed, 21 insertions(+), 2 deletions(-) diff --git a/include/linux/gfp.h b/include/linux/gfp.h index 10f653338042..12ab91e2ed57 100644 --- a/include/linux/gfp.h +++ b/include/linux/gfp.h @@ -398,6 +398,7 @@ __meminit void *alloc_pages_exact_nid_noprof(int nid, size_t size, gfp_t gfp_mas extern void __free_pages(struct page *page, unsigned int order); extern void free_pages_nolock(struct page *page, unsigned int order); extern void free_pages(unsigned long addr, unsigned int order); +void free_frozen_pages_zeroed(struct page *page, unsigned int order); #define __free_page(page) __free_pages((page), 0) #define free_page(addr) free_pages((addr), 0) diff --git a/mm/internal.h b/mm/internal.h index 4c33249e03f0..e655385b269c 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -899,7 +899,6 @@ struct page *__alloc_frozen_pages_noprof(gfp_t, unsigned int order, int nid, #define __alloc_frozen_pages(...) \ alloc_hooks(__alloc_frozen_pages_noprof(__VA_ARGS__)) void free_frozen_pages(struct page *page, unsigned int order); -void free_frozen_pages_zeroed(struct page *page, unsigned int order); void free_unref_folios(struct folio_batch *fbatch); #ifdef CONFIG_NUMA diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 2098d569d80c..9311374bbd2d 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -90,6 +90,13 @@ typedef int __bitwise fpi_t; /* Free the page without taking locks. Rely on trylock only. */ #define FPI_TRYLOCK ((__force fpi_t)BIT(2)) +/* + * The page contents are known to be zero (e.g., the host zeroed them + * during balloon deflate). Set PageZeroed after free so the next + * allocation can skip redundant zeroing. + */ +#define FPI_ZEROED ((__force fpi_t)BIT(3)) + /* prevent >1 _updater_ of zone percpu pageset ->high and ->batch fields */ static DEFINE_MUTEX(pcp_batch_high_lock); #define MIN_PERCPU_PAGELIST_HIGH_FRACTION (8) @@ -1611,8 +1618,11 @@ static void __free_pages_ok(struct page *page, unsigned int order, unsigned long pfn = page_to_pfn(page); struct zone *zone = page_zone(page); - if (__free_pages_prepare(page, order, fpi_flags)) + if (__free_pages_prepare(page, order, fpi_flags)) { + if (fpi_flags & FPI_ZEROED) + __SetPageZeroed(page); free_one_page(zone, page, pfn, order, fpi_flags); + } } void __meminit __free_pages_core(struct page *page, unsigned int order, @@ -3012,6 +3022,9 @@ static void __free_frozen_pages(struct page *page, unsigned int order, if (!__free_pages_prepare(page, order, fpi_flags)) return; + if (fpi_flags & FPI_ZEROED) + __SetPageZeroed(page); + /* * We only track unmovable, reclaimable and movable on pcp lists. * Place ISOLATE pages on the isolated list because they are being @@ -3050,6 +3063,12 @@ void free_frozen_pages(struct page *page, unsigned int order) __free_frozen_pages(page, order, FPI_NONE); } +void free_frozen_pages_zeroed(struct page *page, unsigned int order) +{ + __free_frozen_pages(page, order, FPI_ZEROED); +} +EXPORT_SYMBOL(free_frozen_pages_zeroed); + void free_frozen_pages_nolock(struct page *page, unsigned int order) { __free_frozen_pages(page, order, FPI_TRYLOCK); -- MST