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 A521A1EB19B for ; Tue, 19 May 2026 00:19:49 +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=1779149989; cv=none; b=U3xWALAe+yh1irHAEpouOiqarTjEiET5ARDp/Qnv6EGlWnz9PtLvgyPgqZMu3JWpwbwnlEB6FUZwPsmnlIk9V/wXHVXAhowmS3vXoWWiE8J/LPza4QxApk5dDBNYPDX+lliJzV5AenF63R+kJA/LaB1ry68aFRfsxA7rVgsk8rI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779149989; c=relaxed/simple; bh=Hzt/De4mOk+Mrf1ClqEzbjx7/3o5fPwlCY7Yl8WAxDo=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=hjbTPKnQwQS6Q8BlX7EzqkDz3SIpAFRTgGa8x5V/rZXtXEGFdKci8ULYALsYpW5CWjbhwfIKP8jRp+qlu7QUZHNjw9xmAL68b+9LhiCAbH52Jx6BZn3rUxp6/YvkQZP4uXUtUndQh7UmE/8lUm9U/r/J03Kjz+4p10zCIEhMDFA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=fP+rcvHj; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="fP+rcvHj" Received: by smtp.kernel.org (Postfix) with ESMTPS id 86E48C2BCB7; Tue, 19 May 2026 00:19:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1779149989; bh=Hzt/De4mOk+Mrf1ClqEzbjx7/3o5fPwlCY7Yl8WAxDo=; h=From:Date:Subject:References:In-Reply-To:To:Cc:Reply-To:From; b=fP+rcvHjoZRdF3Es0PDdaC8inQibLP81EnJeouUhnH0sNoDR2R5iV/YDhxIVzMCJg rDVz4sWtRyHnbaGNA+iozbhkAlHLLHyH9DR+d52pcqx6f8oy225qebN50jDA1ayC+x lAB0zpd1/25JPHiic18kb4de5VqJj2d/8ZVd2iGTmcBCO7AAffDiX/qtLdJKMtIyie QEFPHkmb9xUbvW9LQ8iV9Hopb9TWdwnvHWgvZGK1dcjwIBjY6hCa89EMmbPlUTcYJC XgrCVknyiy8fhw8Y6GuxK93APqSnSTwJSMJsUQZj9KxDqiMqtrYLCz/MMH9Be/SOA6 PEhedo1UJnFkA== Received: from aws-us-west-2-korg-lkml-1.web.codeaurora.org (localhost.localdomain [127.0.0.1]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7AFF0CD343F; Tue, 19 May 2026 00:19:49 +0000 (UTC) From: Ackerley Tng via B4 Relay Date: Mon, 18 May 2026 17:19:45 -0700 Subject: [PATCH v3 6/6] mm: hugetlb: Refactor out hugetlb_alloc_folio() Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260518-hugetlb-open-up-v3-6-e14b302477f8@google.com> References: <20260518-hugetlb-open-up-v3-0-e14b302477f8@google.com> In-Reply-To: <20260518-hugetlb-open-up-v3-0-e14b302477f8@google.com> To: Muchun Song , Oscar Salvador , David Hildenbrand , Andrew Morton , fvdl@google.com, jiaqiyan@google.com, joshua.hahnjy@gmail.com, jthoughton@google.com, mhocko@kernel.org, michael.roth@amd.com, pasha.tatashin@soleen.com, pbonzini@redhat.com, peterx@redhat.com, pratyush@kernel.org, rick.p.edgecombe@intel.com, rientjes@google.com, roman.gushchin@linux.dev, seanjc@google.com, shakeel.butt@linux.dev, shivankg@amd.com, vannapurve@google.com, yan.y.zhao@intel.com, Zi Yan , Matthew Brost , Rakie Kim , Byungchul Park , Gregory Price , Ying Huang , Alistair Popple , Dan Williams , Jason Gunthorpe Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Ackerley Tng X-Mailer: b4 0.14.3 X-Developer-Signature: v=1; a=ed25519-sha256; t=1779149988; l=10377; i=ackerleytng@google.com; s=20260225; h=from:subject:message-id; bh=Rm+Th8lyn4N0VMVm3x2XIXppuej/2vu+OQYaa8lCewA=; b=y6o3OBX386APgcc0m2g7ZJsWrHXUNu6KGXPM0gA4cXK8pSE2pB9R+d+OoAfGl2fStV8hvVFTI nI3r4KVxx/mDHvHL5ItCeqgiwEdJpbJJJwg6p6VZpBHT3nLu5QeiwDv X-Developer-Key: i=ackerleytng@google.com; a=ed25519; pk=sAZDYXdm6Iz8FHitpHeFlCMXwabodTm7p8/3/8xUxuU= X-Endpoint-Received: by B4 Relay for ackerleytng@google.com/20260225 with auth_id=649 X-Original-From: Ackerley Tng Reply-To: ackerleytng@google.com From: Ackerley Tng Refactor out hugetlb_alloc_folio() from alloc_hugetlb_folio(), which handles allocation of a folio and memory and HugeTLB charging to cgroups. This refactoring decouples the HugeTLB page allocation from VMAs, specifically: 1. Reservations (as in resv_map) are stored in the vma 2. mpol is stored at vma->vm_policy 3. A vma must be used for allocation even if the pages are not meant to be used by host process. Without this coupling, VMAs are no longer a requirement for allocation. This opens up the allocation routine for usage without VMAs, which will allow guest_memfd to use HugeTLB as a more generic allocator of huge pages, since guest_memfd memory may not have any associated VMAs by design. In addition, direct allocations from HugeTLB could possibly be refactored to avoid the use of a pseudo-VMA. Also, this decouples HugeTLB page allocation from HugeTLBfs, where the subpool is stored at the fs mount. This is also a requirement for guest_memfd, where the plan is to have a subpool created per-fd and stored on the inode. Provide and use alloc_flags to allow more allocation knobs in future without expanding the number of parameters in hugetlb_alloc_folio(). No functional change intended. Signed-off-by: Ackerley Tng --- include/linux/hugetlb.h | 19 +++++ mm/hugetlb.c | 188 +++++++++++++++++++++++++----------------------- 2 files changed, 117 insertions(+), 90 deletions(-) diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index 93418625d3c5f..9a0222851573d 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -2,6 +2,7 @@ #ifndef _LINUX_HUGETLB_H #define _LINUX_HUGETLB_H +#include #include #include #include @@ -705,6 +706,24 @@ bool hugetlb_bootmem_page_zones_valid(int nid, struct huge_bootmem_page *m); int isolate_or_dissolve_huge_folio(struct folio *folio, struct list_head *list); int replace_free_hugepage_folios(unsigned long start_pfn, unsigned long end_pfn); void wait_for_freed_hugetlb_folios(void); + +struct mempolicy_interpreted { + int nid; + nodemask_t *nodemask; + enum mempolicy_mode mode; +}; + +enum hugetlb_alloc_flag { + HUGETLB_ALLOC_CHARGE_CGROUP_RSVD_BIT = 0, + HUGETLB_ALLOC_USE_GLOBAL_RESERVATIONS_BIT, +}; + +#define HUGETLB_ALLOC_CHARG_CGROUP_RSVD BIT(HUGETLB_ALLOC_CHARGE_CGROUP_RSVD_BIT) +#define HUGETLB_ALLOC_USE_GLOBAL_RESERVATIONS BIT(HUGETLB_ALLOC_USE_GLOBAL_RESERVATIONS_BIT) + +struct folio *hugetlb_alloc_folio(struct hstate *h, struct hugepage_subpool *spool, + gfp_t gfp, struct mempolicy_interpreted *mpoli, + u8 alloc_flags); struct folio *alloc_hugetlb_folio(struct vm_area_struct *vma, unsigned long addr, bool cow_from_owner); struct folio *alloc_hugetlb_folio_nodemask(struct hstate *h, int preferred_nid, diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 81e73186dff09..abce2ca76fb9c 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -1334,12 +1334,6 @@ static unsigned long available_huge_pages(struct hstate *h) return h->free_huge_pages - h->resv_huge_pages; } -struct mempolicy_interpreted { - int nid; - nodemask_t *nodemask; - enum mempolicy_mode mode; -}; - static struct folio *dequeue_hugetlb_folio(struct hstate *h, gfp_t gfp_mask, struct mempolicy_interpreted *mpoli) { @@ -2829,6 +2823,90 @@ void wait_for_freed_hugetlb_folios(void) flush_work(&free_hpage_work); } +struct folio *hugetlb_alloc_folio(struct hstate *h, struct hugepage_subpool *spool, + gfp_t gfp, struct mempolicy_interpreted *mpoli, + u8 alloc_flags) +{ + bool charge_hugetlb_cgroup_rsvd = alloc_flags & + HUGETLB_ALLOC_CHARG_CGROUP_RSVD; + bool use_global_reservation = alloc_flags & + HUGETLB_ALLOC_USE_GLOBAL_RESERVATIONS; + size_t nr_pages = pages_per_huge_page(h); + struct hugetlb_cgroup *h_cg = NULL; + int idx = hstate_index(h); + struct folio *folio; + int ret; + + if (charge_hugetlb_cgroup_rsvd && + hugetlb_cgroup_charge_cgroup_rsvd(idx, nr_pages, &h_cg)) + return ERR_PTR(-ENOSPC); + + if (hugetlb_cgroup_charge_cgroup(idx, nr_pages, &h_cg)) { + ret = -ENOSPC; + goto err_uncharge_hugetlb_cgroup_rsvd; + } + + spin_lock_irq(&hugetlb_lock); + + folio = NULL; + if (use_global_reservation || available_huge_pages(h)) + folio = dequeue_hugetlb_folio(h, gfp, mpoli); + + if (!folio) { + spin_unlock_irq(&hugetlb_lock); + folio = alloc_buddy_hugetlb_folio(h, gfp, mpoli); + if (!folio) { + ret = -ENOSPC; + goto err_uncharge_hugetlb_cgroup; + } + spin_lock_irq(&hugetlb_lock); + list_add(&folio->lru, &h->hugepage_activelist); + folio_ref_unfreeze(folio, 1); + } + + if (use_global_reservation) { + folio_set_hugetlb_restore_reserve(folio); + h->resv_huge_pages--; + } + + hugetlb_cgroup_commit_charge(idx, pages_per_huge_page(h), h_cg, folio); + + if (charge_hugetlb_cgroup_rsvd) { + hugetlb_cgroup_commit_charge_rsvd(idx, pages_per_huge_page(h), + h_cg, folio); + } + + spin_unlock_irq(&hugetlb_lock); + + ret = mem_cgroup_charge_hugetlb(folio, gfp | __GFP_RETRY_MAYFAIL); + /* + * Unconditionally increment NR_HUGETLB here because if + * mem_cgroup_charge_hugetlb failed, freeing the page will + * decrement NR_HUGETLB. + */ + lruvec_stat_mod_folio(folio, NR_HUGETLB, pages_per_huge_page(h)); + + if (ret == -ENOMEM) { + free_huge_folio(folio); + /* + * Skip uncharging hugetlb_cgroup since the charges + * were committed to the folio and freeing the folio + * would have cleared those up. + */ + return ERR_PTR(ret); + } + + return folio; + + err_uncharge_hugetlb_cgroup: + hugetlb_cgroup_uncharge_cgroup(idx, nr_pages, h_cg); + err_uncharge_hugetlb_cgroup_rsvd: + if (charge_hugetlb_cgroup_rsvd) + hugetlb_cgroup_uncharge_cgroup_rsvd(idx, nr_pages, h_cg); + + return ERR_PTR(ret); +} + typedef enum { /* * For either 0/1: we checked the per-vma resv map, and one resv @@ -2864,11 +2942,11 @@ struct folio *alloc_hugetlb_folio(struct vm_area_struct *vma, long retval, gbl_chg, gbl_reserve; map_chg_state map_chg; int ret, idx; - struct hugetlb_cgroup *h_cg = NULL; struct mempolicy_interpreted mpoli; gfp_t gfp = htlb_alloc_mask(h); struct mempolicy *mpol; nodemask_t *nodemask; + u8 alloc_flags = 0; int nid; idx = hstate_index(h); @@ -2916,23 +2994,18 @@ struct folio *alloc_hugetlb_folio(struct vm_area_struct *vma, } /* - * If this allocation is not consuming a per-vma reservation, - * charge the hugetlb cgroup now. + * If allocation doesn't reuse a reservation in the resv_map, + * charge for the reservation. */ - if (map_chg) { - ret = hugetlb_cgroup_charge_cgroup_rsvd( - idx, pages_per_huge_page(h), &h_cg); - if (ret) { - ret = -ENOSPC; - goto out_subpool_put; - } - } + if (map_chg != MAP_CHG_REUSE) + alloc_flags |= HUGETLB_ALLOC_CHARG_CGROUP_RSVD; - ret = hugetlb_cgroup_charge_cgroup(idx, pages_per_huge_page(h), &h_cg); - if (ret) { - ret = -ENOSPC; - goto out_uncharge_cgroup_reservation; - } + /* + * gbl_chg == 0 indicates a reservation exists for this + * allocation, so try to use it. + */ + if (gbl_chg == 0) + alloc_flags |= HUGETLB_ALLOC_USE_GLOBAL_RESERVATIONS; /* Takes reference on mpol. */ nid = huge_node(vma, addr, gfp, &mpol, &nodemask); @@ -2942,70 +3015,12 @@ struct folio *alloc_hugetlb_folio(struct vm_area_struct *vma, .nodemask = nodemask, }; - spin_lock_irq(&hugetlb_lock); - - /* - * gbl_chg == 0 indicates a reservation exists for the - * allocation, so try dequeuing a page. In case there was no - * reservation, try dequeuing a page if there are available - * pages in the global pool. - */ - folio = NULL; - if (!gbl_chg || available_huge_pages(h)) - folio = dequeue_hugetlb_folio(h, gfp, &mpoli); - - if (!folio) { - spin_unlock_irq(&hugetlb_lock); - folio = alloc_buddy_hugetlb_folio(h, gfp, &mpoli); - mpol_cond_put(mpol); - if (!folio) { - mpol_cond_put(mpol); - ret = -ENOSPC; - goto out_uncharge_cgroup; - } - spin_lock_irq(&hugetlb_lock); - list_add(&folio->lru, &h->hugepage_activelist); - folio_ref_unfreeze(folio, 1); - /* Fall through */ - } + folio = hugetlb_alloc_folio(h, spool, gfp, &mpoli, alloc_flags); mpol_cond_put(mpol); - /* - * Either dequeued or buddy-allocated folio needs to add special - * mark to the folio when it consumes a global reservation. - */ - if (!gbl_chg) { - folio_set_hugetlb_restore_reserve(folio); - h->resv_huge_pages--; - } - - hugetlb_cgroup_commit_charge(idx, pages_per_huge_page(h), h_cg, folio); - /* If allocation is not consuming a reservation, also store the - * hugetlb_cgroup pointer on the page. - */ - if (map_chg) { - hugetlb_cgroup_commit_charge_rsvd(idx, pages_per_huge_page(h), - h_cg, folio); - } - - spin_unlock_irq(&hugetlb_lock); - - ret = mem_cgroup_charge_hugetlb(folio, gfp | __GFP_RETRY_MAYFAIL); - /* - * Unconditionally increment NR_HUGETLB here. If it turns out that - * mem_cgroup_charge_hugetlb failed, then immediately free the page and - * decrement NR_HUGETLB. - */ - lruvec_stat_mod_folio(folio, NR_HUGETLB, pages_per_huge_page(h)); - - if (ret == -ENOMEM) { - free_huge_folio(folio); - /* - * Skip uncharging hugetlb_cgroup since the charges - * were committed to the folio and freeing the folio - * would have cleared those up. - */ + if (IS_ERR(folio)) { + ret = PTR_ERR(folio); goto out_subpool_put; } @@ -3038,12 +3053,6 @@ struct folio *alloc_hugetlb_folio(struct vm_area_struct *vma, return folio; -out_uncharge_cgroup: - hugetlb_cgroup_uncharge_cgroup(idx, pages_per_huge_page(h), h_cg); -out_uncharge_cgroup_reservation: - if (map_chg) - hugetlb_cgroup_uncharge_cgroup_rsvd(idx, pages_per_huge_page(h), - h_cg); out_subpool_put: /* * put page to subpool iff the quota of subpool's rsv_hpages is used @@ -3054,7 +3063,6 @@ struct folio *alloc_hugetlb_folio(struct vm_area_struct *vma, hugetlb_acct_memory(h, -gbl_reserve); } - out_end_reservation: if (map_chg != MAP_CHG_ENFORCED) vma_end_reservation(h, vma, addr); -- 2.54.0.563.g4f69b47b94-goog