From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-174.mta0.migadu.com (out-174.mta0.migadu.com [91.218.175.174]) (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 5FD1F22301 for ; Sat, 27 Jun 2026 07:28:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.174 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782545303; cv=none; b=Qb8zLJE8nss1I0aOWIcbiFpx6Eg+OqQbn48CUhGYfhDfPM+LMj9MlW2TmiHnifoolaEMsT5hJlTfa34Ngu8LqDBCPI1wW6mRK3pK5FssZFMMd4FBszrdyc7NnBh+kw+lmD6JIlkL6zmk/6+CjUlhPA70uBjdxtXz4S+LPlkilw0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782545303; c=relaxed/simple; bh=nR6Y+GiIL5IyhPojYlt1zMi+tU3NzHnhk88VV7Ln6pc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Rn5cYKoCcSl9mQnXgP4Y1LflV/iEsqpgOgvOcmGl0m0KSiHMsmUaeYKXYyLbFRrz9cCsZ+Ec7tmf0lu6xbOe4clv/jmXmSqXA9p3m/B2Oz7RKY39Y48tTMP0fjAYUKAGkbWis75TlaE+11WVuNhW4Za8hOmyoxAAFTneKB4xpuo= 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=X7Egz2Y/; arc=none smtp.client-ip=91.218.175.174 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="X7Egz2Y/" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1782545300; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=smajn29rHFOT4MtyJVi/R4P7juDmV113b9H8N2iquf8=; b=X7Egz2Y/3kNgx936KgThNiTP1CtcNpl89b1xaYU349h/ZUp1X1ciL0yJVdsMVamhVtvOhu tHt1ZySq9gv19gJ1Y3mMFbiVURl6A0d1o3Jh/F62VE+klH8Dt6bnpdTRDY1r+ySuRI1R2l 7ZgQOSH83Y2dJVk21qRAj9Y3qA3BB/8= From: Qi Zheng To: akpm@linux-foundation.org, david@kernel.org, ljs@kernel.org, ziy@nvidia.com, baolin.wang@linux.alibaba.com, liam@infradead.org, npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, lance.yang@linux.dev, muchun.song@linux.dev, osalvador@suse.de, chrisl@kernel.org, kasong@tencent.com, shikemeng@huaweicloud.com, nphamcs@gmail.com, baoquan.he@linux.dev, youngjun.park@lge.com, peterx@redhat.com, usama.arif@linux.dev, willy@infradead.org, vbabka@kernel.org, surenb@google.com, mhocko@suse.com, jackmanb@google.com, hannes@cmpxchg.org Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Qi Zheng Subject: [RFC PATCH 7/8] mm: support reserved THP VMAs in anonymous faults Date: Sat, 27 Jun 2026 15:26:43 +0800 Message-ID: <8d14f837be754414b9eade37b8409be10a91c7b8.1782538002.git.zhengqi.arch@bytedance.com> In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT From: Qi Zheng Wire VM_RESERVED_THP into the anonymous PMD fault path. For reserved THP VMAs, the faulting folio is requested with the __GFP_RESERVED_THP flag, restricting the allocation to reserved THP pageblocks. The resulting folio remains a normal anonymous THP, using the existing reclaim, swap, and buddy paths. Additionally, enforce that reserved THP faults must either successfully install a PMD-sized folio or fail completely. Fallbacks to the huge zero page or small anonymous pages are not allowed if the PMD-sized allocation fails. Signed-off-by: Qi Zheng --- include/linux/huge_mm.h | 4 +++- mm/huge_memory.c | 18 +++++++++++++----- mm/memory.c | 3 +++ 3 files changed, 19 insertions(+), 6 deletions(-) diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h index ad20f7f8c1794..4fe9651cd86b5 100644 --- a/include/linux/huge_mm.h +++ b/include/linux/huge_mm.h @@ -330,6 +330,8 @@ unsigned long thp_vma_allowable_orders(struct vm_area_struct *vma, if (vm_flags & VM_HUGEPAGE) mask |= READ_ONCE(huge_anon_orders_madvise); + if (vm_flags & VM_RESERVED_THP) + mask |= BIT(PMD_ORDER); if (hugepage_global_always() || ((vm_flags & VM_HUGEPAGE) && hugepage_global_enabled())) mask |= READ_ONCE(huge_anon_orders_inherit); @@ -371,7 +373,7 @@ static inline bool vma_thp_disabled(struct vm_area_struct *vma, * Are THPs disabled only for VMAs where we didn't get an explicit * advise to use them? */ - if (vm_flags & VM_HUGEPAGE) + if (vm_flags & (VM_HUGEPAGE | VM_RESERVED_THP)) return false; /* * Forcing a collapse (e.g., madv_collapse), is a clear advice to diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 2bccb0a53a0a6..66d85a2fa855f 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1267,6 +1267,9 @@ static struct folio *vma_alloc_anon_folio_pmd(struct vm_area_struct *vma, const int order = HPAGE_PMD_ORDER; struct folio *folio; + if (vma->vm_flags & VM_RESERVED_THP) + gfp |= __GFP_RESERVED_THP; + folio = vma_alloc_folio(gfp, order, vma, addr & HPAGE_PMD_MASK); if (unlikely(!folio)) { @@ -1344,8 +1347,11 @@ static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf) vm_fault_t ret = 0; folio = vma_alloc_anon_folio_pmd(vma, vmf->address); - if (unlikely(!folio)) + if (unlikely(!folio)) { + if (vma->vm_flags & VM_RESERVED_THP) + return VM_FAULT_OOM; return VM_FAULT_FALLBACK; + } pgtable = pte_alloc_one(vma->vm_mm); if (unlikely(!pgtable)) { @@ -1480,15 +1486,17 @@ vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf) vm_fault_t ret; if (!thp_vma_suitable_order(vma, haddr, PMD_ORDER)) - return VM_FAULT_FALLBACK; + return (vma->vm_flags & VM_RESERVED_THP) ? VM_FAULT_OOM : + VM_FAULT_FALLBACK; ret = vmf_anon_prepare(vmf); if (ret) return ret; khugepaged_enter_vma(vma, vma->vm_flags); - if (!(vmf->flags & FAULT_FLAG_WRITE) && - !mm_forbids_zeropage(vma->vm_mm) && - transparent_hugepage_use_zero_page()) { + if (!(vma->vm_flags & VM_RESERVED_THP) && + !(vmf->flags & FAULT_FLAG_WRITE) && + !mm_forbids_zeropage(vma->vm_mm) && + transparent_hugepage_use_zero_page()) { pgtable_t pgtable; struct folio *zero_folio; vm_fault_t ret; diff --git a/mm/memory.c b/mm/memory.c index ff338c2abe923..225fc1ae22386 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -5297,6 +5297,9 @@ static vm_fault_t do_anonymous_page(struct vm_fault *vmf) if (vma->vm_flags & VM_SHARED) return VM_FAULT_SIGBUS; + if (unlikely(vma->vm_flags & VM_RESERVED_THP)) + return VM_FAULT_OOM; + /* * Use pte_alloc() instead of pte_alloc_map(), so that OOM can * be distinguished from a transient failure of pte_offset_map(). -- 2.54.0