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[80.230.25.21]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-48a4b329542sm43629625e9.3.2026.04.20.05.50.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 20 Apr 2026 05:50:46 -0700 (PDT) Date: Mon, 20 Apr 2026 08:50:43 -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 , linux-mm@kvack.org, virtualization@lists.linux.dev, Muchun Song , Oscar Salvador Subject: [PATCH RFC v2 09/18] mm: hugetlb: use PG_zeroed for pool pages, skip redundant zeroing Message-ID: 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: HOisB1ehO-PPRcA-kQLG84HFk9LpkO4mxzdMsLE-MG8_1776689447 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline X-Rspamd-Queue-Id: 58237A000C X-Stat-Signature: aoq84rugndmnspxao8z1txk1cwpwpfc7 X-Rspam-User: X-Rspamd-Server: rspam09 X-HE-Tag: 1776689450-960433 X-HE-Meta: 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 y3GKTha2 zpX8ZuJeSFXNdXHuyD2d6StLZl3rPfXSaYHf6ouuGG0hwEI/MQWpRx9K4g5qQOM8gJNO1IeXxcH36+x0TJ4qgc0bP8+qhoUsrlpz8f8zJiWnnbFa60URXsq1RzOK9gPZJVmYzU3yXHwPLZGFdLndP/Sq9JMCt20WUmixe2+CVlTXsi0H/VGtKcwxlZIQg6BoYto0dqn1HZiJIXJ00Xa7M+p3fJKWv8cdxpQlp3v+0DczKdUWK9rulE938u/3/r/oXXvWdgVN+iCy2P3fG5qLjuKmSzzkb4eOi3ERm/qPhQ52cYrJ1r7iyfs4Bbaixcdda0kD8Z6Urg9VFR6ZlDvDBaWFuNog0xn3NjyMMslw5a/uVmrUuCPw9botlCw== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Set PG_zeroed on surplus hugetlb pages when buddy-allocated with PGHINT_ZEROED (indicating the page was pre-zeroed by the host). Clear PG_zeroed in free_huge_folio() when a user-mapped page returns to the pool. Check PG_zeroed at fault and fallocate callers to skip redundant folio_zero_user(). Signed-off-by: Michael S. Tsirkin Assisted-by: Claude:claude-opus-4-6 Assisted-by: cursor-agent:GPT-5.4-xhigh --- fs/hugetlbfs/inode.c | 5 ++++- mm/hugetlb.c | 31 +++++++++++++++++++++---------- 2 files changed, 25 insertions(+), 11 deletions(-) diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c index 3f70c47981de..3f9bdb5a7c85 100644 --- a/fs/hugetlbfs/inode.c +++ b/fs/hugetlbfs/inode.c @@ -828,7 +828,10 @@ static long hugetlbfs_fallocate(struct file *file, int mode, loff_t offset, error = PTR_ERR(folio); goto out; } - folio_zero_user(folio, addr); + if (PageZeroed(&folio->page)) + __ClearPageZeroed(&folio->page); + else + folio_zero_user(folio, addr); __folio_mark_uptodate(folio); error = hugetlb_add_to_page_cache(folio, mapping, index); if (unlikely(error)) { diff --git a/mm/hugetlb.c b/mm/hugetlb.c index faa94a114fd4..704ec0817c5e 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -1746,6 +1746,8 @@ void free_huge_folio(struct folio *folio) bool restore_reserve; unsigned long flags; + __ClearPageZeroed(&folio->page); + VM_BUG_ON_FOLIO(folio_ref_count(folio), folio); VM_BUG_ON_FOLIO(folio_mapcount(folio), folio); @@ -1919,12 +1921,13 @@ static struct folio *only_alloc_fresh_hugetlb_folio(struct hstate *h, * pages is zero, and the accounting must be done in the caller. */ static struct folio *alloc_fresh_hugetlb_folio(struct hstate *h, - gfp_t gfp_mask, int nid, nodemask_t *nmask) + gfp_t gfp_mask, int nid, nodemask_t *nmask, + pghint_t *hints) { struct folio *folio; folio = only_alloc_fresh_hugetlb_folio(h, gfp_mask, nid, nmask, - NULL, NULL); + NULL, hints); if (folio) hugetlb_vmemmap_optimize_folio(h, folio); return folio; @@ -2137,6 +2140,7 @@ static struct folio *alloc_surplus_hugetlb_folio(struct hstate *h, gfp_t gfp_mask, int nid, nodemask_t *nmask) { struct folio *folio = NULL; + pghint_t hints; if (hstate_is_gigantic_no_runtime(h)) return NULL; @@ -2146,10 +2150,13 @@ static struct folio *alloc_surplus_hugetlb_folio(struct hstate *h, goto out_unlock; spin_unlock_irq(&hugetlb_lock); - folio = alloc_fresh_hugetlb_folio(h, gfp_mask, nid, nmask); + folio = alloc_fresh_hugetlb_folio(h, gfp_mask, nid, nmask, &hints); if (!folio) return NULL; + if (hints & PGHINT_ZEROED) + __SetPageZeroed(&folio->page); + spin_lock_irq(&hugetlb_lock); /* * nr_huge_pages needs to be adjusted within the same lock cycle @@ -2189,7 +2196,7 @@ static struct folio *alloc_migrate_hugetlb_folio(struct hstate *h, gfp_t gfp_mas if (hstate_is_gigantic(h)) return NULL; - folio = alloc_fresh_hugetlb_folio(h, gfp_mask, nid, nmask); + folio = alloc_fresh_hugetlb_folio(h, gfp_mask, nid, nmask, NULL); if (!folio) return NULL; @@ -2242,9 +2249,6 @@ struct folio *alloc_hugetlb_folio_reserve(struct hstate *h, int preferred_nid, { struct folio *folio; - if (hints) - *hints = (pghint_t)0; - spin_lock_irq(&hugetlb_lock); if (!h->resv_huge_pages) { spin_unlock_irq(&hugetlb_lock); @@ -2253,8 +2257,12 @@ struct folio *alloc_hugetlb_folio_reserve(struct hstate *h, int preferred_nid, folio = dequeue_hugetlb_folio_nodemask(h, gfp_mask, preferred_nid, nmask); - if (folio) + if (folio) { h->resv_huge_pages--; + if (hints) + *hints = PageZeroed(&folio->page) ? PGHINT_ZEROED : 0; + __ClearPageZeroed(&folio->page); + } spin_unlock_irq(&hugetlb_lock); return folio; @@ -2748,7 +2756,7 @@ static int alloc_and_dissolve_hugetlb_folio(struct folio *old_folio, spin_unlock_irq(&hugetlb_lock); gfp_mask = htlb_alloc_mask(h) | __GFP_THISNODE; new_folio = alloc_fresh_hugetlb_folio(h, gfp_mask, - nid, NULL); + nid, NULL, NULL); if (!new_folio) return -ENOMEM; goto retry; @@ -5820,7 +5828,10 @@ static vm_fault_t hugetlb_no_page(struct address_space *mapping, ret = 0; goto out; } - folio_zero_user(folio, vmf->real_address); + if (PageZeroed(&folio->page)) + __ClearPageZeroed(&folio->page); + else + folio_zero_user(folio, vmf->real_address); __folio_mark_uptodate(folio); new_folio = true; -- MST