From patchwork Thu Jun 13 08:38:09 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Qi Zheng X-Patchwork-Id: 13696347 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id CC56BC27C4F for ; Thu, 13 Jun 2024 08:39:22 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 61E7A6B00A1; Thu, 13 Jun 2024 04:39:22 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 5A70D6B00A2; Thu, 13 Jun 2024 04:39:22 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 41FAC6B00A3; Thu, 13 Jun 2024 04:39:22 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id 235D76B00A1 for ; Thu, 13 Jun 2024 04:39:22 -0400 (EDT) Received: from smtpin13.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id CF77DA39A6 for ; Thu, 13 Jun 2024 08:39:21 +0000 (UTC) X-FDA: 82225216122.13.7D5C919 Received: from mail-oa1-f41.google.com (mail-oa1-f41.google.com [209.85.160.41]) by imf02.hostedemail.com (Postfix) with ESMTP id 0D27780002 for ; Thu, 13 Jun 2024 08:39:19 +0000 (UTC) Authentication-Results: imf02.hostedemail.com; dkim=pass header.d=bytedance.com header.s=google header.b=aEZi95Lf; spf=pass (imf02.hostedemail.com: domain of zhengqi.arch@bytedance.com designates 209.85.160.41 as permitted sender) smtp.mailfrom=zhengqi.arch@bytedance.com; dmarc=pass (policy=quarantine) header.from=bytedance.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1718267959; a=rsa-sha256; cv=none; b=IXAUasEPgeWgmOhDBYuykaCTszuBJDwjoY3dcgH2U9hpBhgVKCTeGeXnfUnZAM2djK01YS uVUaOOUFvRI/f7M/SBbwXWbg3JmBiR1kEdcEkWCx2Pyjd68pdW8D4ZXDSdTEJdMrWZxTwj Kf7qYlXrpUEmvGHETPwOh0rc/qtf9XY= ARC-Authentication-Results: i=1; imf02.hostedemail.com; dkim=pass header.d=bytedance.com header.s=google header.b=aEZi95Lf; spf=pass (imf02.hostedemail.com: domain of zhengqi.arch@bytedance.com designates 209.85.160.41 as permitted sender) smtp.mailfrom=zhengqi.arch@bytedance.com; dmarc=pass (policy=quarantine) header.from=bytedance.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1718267959; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=ChynU9z5JOCMqbjVxFHZ6Asc4dZFXj2+q+uZdr+9n9E=; b=kX4Ar98zSSGzJc5MK3ehIt86/xPH6udMNMKs0+DDATV2YKdMUOUnxmvw6xxdDNeq66FP7L 8HSkl7XdY0OwK2AgTxFdzYWmq5ve0vn87XtDytP7BHzwnylXZQGkcuiJkrmGc2usudXLIM c06w2hQFRrouTjsPMpDjo5pD6E5bLuo= Received: by mail-oa1-f41.google.com with SMTP id 586e51a60fabf-24c582673a5so112344fac.2 for ; Thu, 13 Jun 2024 01:39:19 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance.com; s=google; t=1718267959; x=1718872759; darn=kvack.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=ChynU9z5JOCMqbjVxFHZ6Asc4dZFXj2+q+uZdr+9n9E=; b=aEZi95Lf0/ywzNoLdwT8O1ig5vlRbp3PwbCquyDCbAS46a4ds4eAV05yUJgVINKw7j nVxZkb7Rcsq4ASz2NnVlLKgkaj548n56VKu15AAI6supXQlXwg/6dfR//R+XkKDs3rm5 EiNa9FYVH1nbnCVKo9WyJn8UO6/bbDzit27PiOha1bRfDaFZJr2dX/ZIIJ1/JjOnVP5E WL7CX6aOyWdncbBOKCRWdnz+4M2rG+UEV66kVK5Cj96fXIIwzby5PeOPYhL7GXEhIJWx hvbg1WeAoyA2eHMPAWXjR9rJt1+wL2Q8uNTJjnvwNHoYNNcvCTLj6ODX9u5O+yCckMfx 72lg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1718267959; x=1718872759; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=ChynU9z5JOCMqbjVxFHZ6Asc4dZFXj2+q+uZdr+9n9E=; b=otkt3iH5kKo5BH17j67rbEfE7ZtKnTRiBrqbZb2+G3K6zjJu5eKR12/YR5VHigwlTD ykueAHh2cD0Ylz9PP7nNNzQzDhrOU7yG8apPyQXYavvAAnJPH+8fFQpvRNOy68zAh8vU FJLSkOTXIF06Lw5wWhmiW8/blKHG5ZH86jNzyELNhEvykWNADyzoYvMC12MyjpugFhUb Bb31YrA/7CYAcLENu1boFhhT97mjIIifEDqwmHWvG31xsCDfq2CwgBKrBeP9RcWU59YD E9JZ0P+OBBH9uKFvzicsjgIJiMfNAjtz8EtQJ3XA62bElQNT4/A5beIcKhmnoezJx8n+ Fu3Q== X-Gm-Message-State: AOJu0YxXaGTD0TiUkMCfGC1hqkQpqNgc7i3EZk/eLA+7Dp/n+b5PoB2q jIUrQlxVg1NoUz36CtRNn9PwY15yYhDuK/INQfbxKXnZGXX290+RByCxf6NQ5dE= X-Google-Smtp-Source: AGHT+IG5fRqFeCgKiHECkAvdVDXYqyUQDwS7LLbxLF7n/kGnf0XhUcBBmoT8lkZTDQg4z6Muj8MdhA== X-Received: by 2002:a05:6870:7193:b0:254:a5dd:3772 with SMTP id 586e51a60fabf-25514ef5f91mr4375320fac.4.1718267958799; Thu, 13 Jun 2024 01:39:18 -0700 (PDT) Received: from C02DW0BEMD6R.bytedance.net ([203.208.167.150]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-705ccb980bdsm820856b3a.211.2024.06.13.01.39.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 13 Jun 2024 01:39:18 -0700 (PDT) From: Qi Zheng To: david@redhat.com, hughd@google.com, willy@infradead.org, mgorman@suse.de, muchun.song@linux.dev, akpm@linux-foundation.org Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Qi Zheng Subject: [RFC PATCH 2/3] mm: pgtable: make pte_offset_map_nolock() return pmdval Date: Thu, 13 Jun 2024 16:38:09 +0800 Message-Id: X-Mailer: git-send-email 2.24.3 (Apple Git-128) In-Reply-To: References: MIME-Version: 1.0 X-Stat-Signature: 1p5faq38zhm1de5uq7hid64atfyrgwo5 X-Rspamd-Queue-Id: 0D27780002 X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1718267959-828870 X-HE-Meta: U2FsdGVkX1/Ol3ETLW5hg5D1Jj7/HNDWXSbeovccP5vD1TwUr5JLu77njw7jSODfvuSLAuPukvSFxaRODAsnxnD4d2/le3Pi0gYF3aTwxEVKFGWXYGv62YHW2AUT1dJQfIls3bQhHTyHiEmse7SVvmiMTvTYE3wQ5hr+Cu23/1mX1z0u1FmLdIkp+eMxatrmdKSHnRpj3Utmk/K0zFQgQdILVlU7UJ8hlO3g0aXOsvRNSZ3de7G6c0+MDQjIhigGJo/S+Q6PBP9t5yJ7Bo3zbAVHK99OVU69tJ0eLepmGbAeKIWHWyMJl5EUfxe7Oia1L9V3YDVJSnlFsf5uL2cupvV3bBwgCCCmeAiMH46ZvnykSLxe16ThpWkp+uMUoGnssndTK4H+S5BOiAPs8lL1zTSc3olLEX7AyUrQBmUvSYznEel+i9JKoHhExL2CSUZ74xgpB1vyzus4N18BbPLnQnUx1RP8Zu15QJdEZwMbswLkRZYwPj/HqxC8TdP2kr39rPeUWPBUtqTTycmFFpL7YsQR2MhjGdL29pgon5IWW8MpsSXStMYazFp5u4ZVZruMhxS+K9XGWKALXZ0zI6UBFIi5D3IiDKQeunzG1ucTxzAcPk98gwprhrpDA7Du4fkE4RoGU/BY5H7b2xc+wN2wELJ6GCBca1O9TmsjkzbSXXHpwd93zsgwEyehlZA44SCPhuutM8P0rU7W2l157tCL+ts6qY47YWLsXs/ZxBw/oHm5dvUp+9AB6Y4ysSNLT2WtmAa1DxdxyozA/LiOBu6CvsGCuyteRTC8e8MtIklusBGnJApFBRYPjJXEeysG+oKZhJLiIZY6uybHv6yjEmSwUW8UxFHsFdrOF7KoZHlbTzGGr/wZXdmfwnlQlagkoLC0RJiJaMnhqD9+Yj/bhoJ4JkTQLGCD3Laet1y3XqFtZgJ+8XyOOMWcji+5E6hpFLUWpIyxgqo4fxyR7ZFFRod hbB52SQr Xg8EOnFeWBjLFWEJ5SF28pLYhwISb5R07175USn85QP2Zfi0lChzJT9RjVbEPorlAY2INk2jkwQIBIt71dUQL8OI5Gd64glhTwJsiGjETSGdT0CaYFMPc2j0yv0C27ubBMe8371dN3ne4rfbpSWZvVB771E4hWOCTyqIO1qec2RsnRHLBKDyYsnF/slF0cOsntgDRhXL1GnYQgNcc5+ZGyPYG7xS6yYluK+9+mZncaXcfZFRWPiP4r2foHCaV0eH4tEP4oSA79XOPByD+SGF9pF7hi1UbGin6EIvdyArIv5wMWt/elxBnV1S72hNH9PI4T8vZ9zQSYbj9BXDI2RNmtg0RfYCMukyDtTyy78j7Ky32Mc7XF+ay1Ov8NA== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Make pte_offset_map_nolock() return pmdval so that we can recheck the *pmd once the lock is taken. This is a preparation for freeing empty PTE pages, no functional changes are expected. Signed-off-by: Qi Zheng --- Documentation/mm/split_page_table_lock.rst | 3 ++- arch/arm/mm/fault-armv.c | 2 +- arch/powerpc/mm/pgtable.c | 2 +- include/linux/mm.h | 4 ++-- mm/filemap.c | 2 +- mm/khugepaged.c | 4 ++-- mm/memory.c | 4 ++-- mm/mremap.c | 2 +- mm/page_vma_mapped.c | 2 +- mm/pgtable-generic.c | 21 ++++++++++++--------- mm/userfaultfd.c | 4 ++-- mm/vmscan.c | 2 +- 12 files changed, 28 insertions(+), 24 deletions(-) diff --git a/Documentation/mm/split_page_table_lock.rst b/Documentation/mm/split_page_table_lock.rst index e4f6972eb6c0..e6a47d57531c 100644 --- a/Documentation/mm/split_page_table_lock.rst +++ b/Documentation/mm/split_page_table_lock.rst @@ -18,7 +18,8 @@ There are helpers to lock/unlock a table and other accessor functions: pointer to its PTE table lock, or returns NULL if no PTE table; - pte_offset_map_nolock() maps PTE, returns pointer to PTE with pointer to its PTE table - lock (not taken), or returns NULL if no PTE table; + lock (not taken) and the value of its pmd entry, or returns NULL + if no PTE table; - pte_offset_map() maps PTE, returns pointer to PTE, or returns NULL if no PTE table; - pte_unmap() diff --git a/arch/arm/mm/fault-armv.c b/arch/arm/mm/fault-armv.c index 2286c2ea60ec..3e4ed99b9330 100644 --- a/arch/arm/mm/fault-armv.c +++ b/arch/arm/mm/fault-armv.c @@ -117,7 +117,7 @@ static int adjust_pte(struct vm_area_struct *vma, unsigned long address, * must use the nested version. This also means we need to * open-code the spin-locking. */ - pte = pte_offset_map_nolock(vma->vm_mm, pmd, address, &ptl); + pte = pte_offset_map_nolock(vma->vm_mm, pmd, NULL, address, &ptl); if (!pte) return 0; diff --git a/arch/powerpc/mm/pgtable.c b/arch/powerpc/mm/pgtable.c index 9e7ba9c3851f..ab0250f1b226 100644 --- a/arch/powerpc/mm/pgtable.c +++ b/arch/powerpc/mm/pgtable.c @@ -350,7 +350,7 @@ void assert_pte_locked(struct mm_struct *mm, unsigned long addr) */ if (pmd_none(*pmd)) return; - pte = pte_offset_map_nolock(mm, pmd, addr, &ptl); + pte = pte_offset_map_nolock(mm, pmd, NULL, addr, &ptl); BUG_ON(!pte); assert_spin_locked(ptl); pte_unmap(pte); diff --git a/include/linux/mm.h b/include/linux/mm.h index 106bb0310352..d5550c3dc550 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -2969,8 +2969,8 @@ static inline pte_t *pte_offset_map_lock(struct mm_struct *mm, pmd_t *pmd, return pte; } -pte_t *pte_offset_map_nolock(struct mm_struct *mm, pmd_t *pmd, - unsigned long addr, spinlock_t **ptlp); +pte_t *pte_offset_map_nolock(struct mm_struct *mm, pmd_t *pmd, pmd_t *pmdvalp, + unsigned long addr, spinlock_t **ptlp); #define pte_unmap_unlock(pte, ptl) do { \ spin_unlock(ptl); \ diff --git a/mm/filemap.c b/mm/filemap.c index 37061aafd191..7eb2e3599966 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -3231,7 +3231,7 @@ static vm_fault_t filemap_fault_recheck_pte_none(struct vm_fault *vmf) if (!(vmf->flags & FAULT_FLAG_ORIG_PTE_VALID)) return 0; - ptep = pte_offset_map_nolock(vma->vm_mm, vmf->pmd, vmf->address, + ptep = pte_offset_map_nolock(vma->vm_mm, vmf->pmd, NULL, vmf->address, &vmf->ptl); if (unlikely(!ptep)) return VM_FAULT_NOPAGE; diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 774a97e6e2da..2a8703ee876c 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -992,7 +992,7 @@ static int __collapse_huge_page_swapin(struct mm_struct *mm, }; if (!pte++) { - pte = pte_offset_map_nolock(mm, pmd, address, &ptl); + pte = pte_offset_map_nolock(mm, pmd, NULL, address, &ptl); if (!pte) { mmap_read_unlock(mm); result = SCAN_PMD_NULL; @@ -1581,7 +1581,7 @@ int collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr, if (userfaultfd_armed(vma) && !(vma->vm_flags & VM_SHARED)) pml = pmd_lock(mm, pmd); - start_pte = pte_offset_map_nolock(mm, pmd, haddr, &ptl); + start_pte = pte_offset_map_nolock(mm, pmd, NULL, haddr, &ptl); if (!start_pte) /* mmap_lock + page lock should prevent this */ goto abort; if (!pml) diff --git a/mm/memory.c b/mm/memory.c index 1bd2ffb76ec2..694c0989a1d8 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1108,7 +1108,7 @@ copy_pte_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma, ret = -ENOMEM; goto out; } - src_pte = pte_offset_map_nolock(src_mm, src_pmd, addr, &src_ptl); + src_pte = pte_offset_map_nolock(src_mm, src_pmd, NULL, addr, &src_ptl); if (!src_pte) { pte_unmap_unlock(dst_pte, dst_ptl); /* ret == 0 */ @@ -5486,7 +5486,7 @@ static vm_fault_t handle_pte_fault(struct vm_fault *vmf) * it into a huge pmd: just retry later if so. */ vmf->pte = pte_offset_map_nolock(vmf->vma->vm_mm, vmf->pmd, - vmf->address, &vmf->ptl); + NULL, vmf->address, &vmf->ptl); if (unlikely(!vmf->pte)) return 0; vmf->orig_pte = ptep_get_lockless(vmf->pte); diff --git a/mm/mremap.c b/mm/mremap.c index e7ae140fc640..f672d0218a6f 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -175,7 +175,7 @@ static int move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd, err = -EAGAIN; goto out; } - new_pte = pte_offset_map_nolock(mm, new_pmd, new_addr, &new_ptl); + new_pte = pte_offset_map_nolock(mm, new_pmd, NULL, new_addr, &new_ptl); if (!new_pte) { pte_unmap_unlock(old_pte, old_ptl); err = -EAGAIN; diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c index ae5cc42aa208..507701b7bcc1 100644 --- a/mm/page_vma_mapped.c +++ b/mm/page_vma_mapped.c @@ -33,7 +33,7 @@ static bool map_pte(struct page_vma_mapped_walk *pvmw, spinlock_t **ptlp) * Though, in most cases, page lock already protects this. */ pvmw->pte = pte_offset_map_nolock(pvmw->vma->vm_mm, pvmw->pmd, - pvmw->address, ptlp); + NULL, pvmw->address, ptlp); if (!pvmw->pte) return false; diff --git a/mm/pgtable-generic.c b/mm/pgtable-generic.c index 197937495a0a..b8b28715cb4f 100644 --- a/mm/pgtable-generic.c +++ b/mm/pgtable-generic.c @@ -305,7 +305,7 @@ pte_t *__pte_offset_map(pmd_t *pmd, unsigned long addr, pmd_t *pmdvalp) return NULL; } -pte_t *pte_offset_map_nolock(struct mm_struct *mm, pmd_t *pmd, +pte_t *pte_offset_map_nolock(struct mm_struct *mm, pmd_t *pmd, pmd_t *pmdvalp, unsigned long addr, spinlock_t **ptlp) { pmd_t pmdval; @@ -314,6 +314,8 @@ pte_t *pte_offset_map_nolock(struct mm_struct *mm, pmd_t *pmd, pte = __pte_offset_map(pmd, addr, &pmdval); if (likely(pte)) *ptlp = pte_lockptr(mm, &pmdval); + if (pmdvalp) + *pmdvalp = pmdval; return pte; } @@ -347,14 +349,15 @@ pte_t *pte_offset_map_nolock(struct mm_struct *mm, pmd_t *pmd, * and disconnected table. Until pte_unmap(pte) unmaps and rcu_read_unlock()s * afterwards. * - * pte_offset_map_nolock(mm, pmd, addr, ptlp), above, is like pte_offset_map(); - * but when successful, it also outputs a pointer to the spinlock in ptlp - as - * pte_offset_map_lock() does, but in this case without locking it. This helps - * the caller to avoid a later pte_lockptr(mm, *pmd), which might by that time - * act on a changed *pmd: pte_offset_map_nolock() provides the correct spinlock - * pointer for the page table that it returns. In principle, the caller should - * recheck *pmd once the lock is taken; in practice, no callsite needs that - - * either the mmap_lock for write, or pte_same() check on contents, is enough. + * pte_offset_map_nolock(mm, pmd, pmdvalp, addr, ptlp), above, is like + * pte_offset_map(); but when successful, it also outputs a pointer to the + * spinlock in ptlp - as pte_offset_map_lock() does, but in this case without + * locking it. This helps the caller to avoid a later pte_lockptr(mm, *pmd), + * which might by that time act on a changed *pmd: pte_offset_map_nolock() + * provides the correct spinlock pointer for the page table that it returns. + * In principle, the caller should recheck *pmd once the lock is taken; But in + * most cases, either the mmap_lock for write, or pte_same() check on contents, + * is enough. * * Note that free_pgtables(), used after unmapping detached vmas, or when * exiting the whole mm, does not take page table lock before freeing a page diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index 5e7f2801698a..9c77271d499c 100644 --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -1143,7 +1143,7 @@ static int move_pages_pte(struct mm_struct *mm, pmd_t *dst_pmd, pmd_t *src_pmd, src_addr, src_addr + PAGE_SIZE); mmu_notifier_invalidate_range_start(&range); retry: - dst_pte = pte_offset_map_nolock(mm, dst_pmd, dst_addr, &dst_ptl); + dst_pte = pte_offset_map_nolock(mm, dst_pmd, NULL, dst_addr, &dst_ptl); /* Retry if a huge pmd materialized from under us */ if (unlikely(!dst_pte)) { @@ -1151,7 +1151,7 @@ static int move_pages_pte(struct mm_struct *mm, pmd_t *dst_pmd, pmd_t *src_pmd, goto out; } - src_pte = pte_offset_map_nolock(mm, src_pmd, src_addr, &src_ptl); + src_pte = pte_offset_map_nolock(mm, src_pmd, NULL, src_addr, &src_ptl); /* * We held the mmap_lock for reading so MADV_DONTNEED diff --git a/mm/vmscan.c b/mm/vmscan.c index c0429fd6c573..56727caa907b 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -3374,7 +3374,7 @@ static bool walk_pte_range(pmd_t *pmd, unsigned long start, unsigned long end, DEFINE_MAX_SEQ(walk->lruvec); int old_gen, new_gen = lru_gen_from_seq(max_seq); - pte = pte_offset_map_nolock(args->mm, pmd, start & PMD_MASK, &ptl); + pte = pte_offset_map_nolock(args->mm, pmd, NULL, start & PMD_MASK, &ptl); if (!pte) return false; if (!spin_trylock(ptl)) {