From mboxrd@z Thu Jan 1 00:00:00 1970 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5A2A8C77B7F for ; Mon, 1 May 2023 17:50:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232466AbjEARun (ORCPT ); Mon, 1 May 2023 13:50:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40454 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232535AbjEARug (ORCPT ); Mon, 1 May 2023 13:50:36 -0400 Received: from mail-pf1-x449.google.com (mail-pf1-x449.google.com [IPv6:2607:f8b0:4864:20::449]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 693011BFF for ; Mon, 1 May 2023 10:50:35 -0700 (PDT) Received: by mail-pf1-x449.google.com with SMTP id d2e1a72fcca58-64115e69e1eso23582544b3a.0 for ; Mon, 01 May 2023 10:50:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1682963435; x=1685555435; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=oNrjh4NDZfCOCA+XspYc7I9kB51AWPXlbM0N3pX4I38=; b=Kbw2vWgfaNr9wwaOaALtstqdWrM8vexXN61YFf/VngXG0KW+KOPVkcePNZuJ8BunHG 4fpSDYYnv+oGNFNonvZma1sxd7lY+pamluLU1rV2cF//+7bWNniJgJBWEyyKJ8Vh7+6F 9iUtSaPHWAZ9eK6TXIhhIoxbL87AdOepwayQg5RNHhsGMUhaXjd/xW95LMnIJV5qHKsT ZO0KE701s1k305YVP18qbfaonF6MXOH89tuj3WV3vRzavu+9Gwau1Sh80hFUZAu7ob7d posHsah7zh+ARWr8FuaWg+eUdTnxNa8x9N/3HBaa0SrwutIbbkwlqTQY4bXjTqb8TVCJ gauQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1682963435; x=1685555435; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=oNrjh4NDZfCOCA+XspYc7I9kB51AWPXlbM0N3pX4I38=; b=cFfmUGqI/Z7NTtc3PSOZgPE077NieSKg9RfGtSX0WAhi4o08xIMw8ZIG1YcCNXf4g8 W9IkN18WhW8iVnkOowp+HmwIlY+8dWL8UCbCV40lFPspgyjsZztkwT1bUbKSGc/ApTi4 CpY2xekRBWORgWDi+17GQx1WCMYtn0aCQC7AYVGJbYiT4bHSKh1U/iMe4mnAuJywbwZ8 cb+irqz55yrz2188nt22dlXaNqpVXUOS3R9KwIVAHJ59gjBEiLmy7zjJMJnP/yTnVPFX aTdjRFQ6Wytz3ZWG9XZHxnOzAeDxH2wW4PX7nBAZUjPLhEt5Ejt/ZUNAnBu4vtQmxlxJ ui8Q== X-Gm-Message-State: AC+VfDx5Ao2CpMVPpgT/vJnaWKaGoCvHvpr0xn2VKC3WEllER58vSnv1 2pXywJxmZKspJgwVMmwRLFUiCZNYYuA= X-Google-Smtp-Source: ACHHUZ6EimADaT391MpwBUkL6hz/B/GfVS5bvY+TKbOxuncQS8LbI8CgIxJ7ch0/4tBeArriD6dOerX5ZI8= X-Received: from surenb-desktop.mtv.corp.google.com ([2620:15c:211:201:6d24:3efd:facc:7ac4]) (user=surenb job=sendgmr) by 2002:a17:90a:72cc:b0:24d:e14a:6361 with SMTP id l12-20020a17090a72cc00b0024de14a6361mr1794469pjk.3.1682963434788; Mon, 01 May 2023 10:50:34 -0700 (PDT) Date: Mon, 1 May 2023 10:50:25 -0700 In-Reply-To: <20230501175025.36233-1-surenb@google.com> Mime-Version: 1.0 References: <20230501175025.36233-1-surenb@google.com> X-Mailer: git-send-email 2.40.1.495.gc816e09b53d-goog Message-ID: <20230501175025.36233-3-surenb@google.com> Subject: [PATCH 3/3] mm: implement folio wait under VMA lock From: Suren Baghdasaryan To: akpm@linux-foundation.org Cc: willy@infradead.org, hannes@cmpxchg.org, mhocko@suse.com, josef@toxicpanda.com, jack@suse.cz, ldufour@linux.ibm.com, laurent.dufour@fr.ibm.com, michel@lespinasse.org, liam.howlett@oracle.com, jglisse@google.com, vbabka@suse.cz, minchan@google.com, dave@stgolabs.net, punit.agrawal@bytedance.com, lstoakes@gmail.com, hdanton@sina.com, apopple@nvidia.com, surenb@google.com, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@android.com Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Follow the same pattern as mmap_lock when waiting for folio by dropping VMA lock before the wait and retrying once folio is available. Signed-off-by: Suren Baghdasaryan --- include/linux/pagemap.h | 14 ++++++++++---- mm/filemap.c | 43 ++++++++++++++++++++++------------------- mm/memory.c | 13 +++++++++---- 3 files changed, 42 insertions(+), 28 deletions(-) diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index a56308a9d1a4..6c9493314c21 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -896,8 +896,8 @@ static inline bool wake_page_match(struct wait_page_queue *wait_page, void __folio_lock(struct folio *folio); int __folio_lock_killable(struct folio *folio); -bool __folio_lock_or_retry(struct folio *folio, struct mm_struct *mm, - unsigned int flags); +bool __folio_lock_or_retry(struct folio *folio, struct vm_area_struct *vma, + unsigned int flags, bool *lock_dropped); void unlock_page(struct page *page); void folio_unlock(struct folio *folio); @@ -1002,10 +1002,16 @@ static inline int folio_lock_killable(struct folio *folio) * __folio_lock_or_retry(). */ static inline bool folio_lock_or_retry(struct folio *folio, - struct mm_struct *mm, unsigned int flags) + struct vm_area_struct *vma, unsigned int flags, + bool *lock_dropped) { might_sleep(); - return folio_trylock(folio) || __folio_lock_or_retry(folio, mm, flags); + if (folio_trylock(folio)) { + *lock_dropped = false; + return true; + } + + return __folio_lock_or_retry(folio, vma, flags, lock_dropped); } /* diff --git a/mm/filemap.c b/mm/filemap.c index 84f39114d4de..9c0fa8578b2f 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -1701,37 +1701,35 @@ static int __folio_lock_async(struct folio *folio, struct wait_page_queue *wait) /* * Return values: - * true - folio is locked; mmap_lock is still held. + * true - folio is locked. * false - folio is not locked. - * mmap_lock has been released (mmap_read_unlock(), unless flags had both - * FAULT_FLAG_ALLOW_RETRY and FAULT_FLAG_RETRY_NOWAIT set, in - * which case mmap_lock is still held. - * If flags had FAULT_FLAG_VMA_LOCK set, meaning the operation is performed - * with VMA lock only, the VMA lock is still held. + * + * lock_dropped indicates whether mmap_lock/VMA lock got dropped. + * mmap_lock/VMA lock is dropped when function fails to lock the folio, + * unless flags had both FAULT_FLAG_ALLOW_RETRY and FAULT_FLAG_RETRY_NOWAIT + * set, in which case mmap_lock/VMA lock is still held. * * If neither ALLOW_RETRY nor KILLABLE are set, will always return true - * with the folio locked and the mmap_lock unperturbed. + * with the folio locked and the mmap_lock/VMA lock unperturbed. */ -bool __folio_lock_or_retry(struct folio *folio, struct mm_struct *mm, - unsigned int flags) +bool __folio_lock_or_retry(struct folio *folio, struct vm_area_struct *vma, + unsigned int flags, bool *lock_dropped) { - /* Can't do this if not holding mmap_lock */ - if (flags & FAULT_FLAG_VMA_LOCK) - return false; - if (fault_flag_allow_retry_first(flags)) { - /* - * CAUTION! In this case, mmap_lock is not released - * even though return 0. - */ - if (flags & FAULT_FLAG_RETRY_NOWAIT) + if (flags & FAULT_FLAG_RETRY_NOWAIT) { + *lock_dropped = false; return false; + } - mmap_read_unlock(mm); + if (flags & FAULT_FLAG_VMA_LOCK) + vma_end_read(vma); + else + mmap_read_unlock(vma->vm_mm); if (flags & FAULT_FLAG_KILLABLE) folio_wait_locked_killable(folio); else folio_wait_locked(folio); + *lock_dropped = true; return false; } if (flags & FAULT_FLAG_KILLABLE) { @@ -1739,13 +1737,18 @@ bool __folio_lock_or_retry(struct folio *folio, struct mm_struct *mm, ret = __folio_lock_killable(folio); if (ret) { - mmap_read_unlock(mm); + if (flags & FAULT_FLAG_VMA_LOCK) + vma_end_read(vma); + else + mmap_read_unlock(vma->vm_mm); + *lock_dropped = true; return false; } } else { __folio_lock(folio); } + *lock_dropped = false; return true; } diff --git a/mm/memory.c b/mm/memory.c index 8222acf74fd3..e1cd39f00756 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3568,6 +3568,7 @@ static vm_fault_t remove_device_exclusive_entry(struct vm_fault *vmf) struct folio *folio = page_folio(vmf->page); struct vm_area_struct *vma = vmf->vma; struct mmu_notifier_range range; + bool lock_dropped; /* * We need a reference to lock the folio because we don't hold @@ -3580,8 +3581,10 @@ static vm_fault_t remove_device_exclusive_entry(struct vm_fault *vmf) if (!folio_try_get(folio)) return 0; - if (!folio_lock_or_retry(folio, vma->vm_mm, vmf->flags)) { + if (!folio_lock_or_retry(folio, vma, vmf->flags, &lock_dropped)) { folio_put(folio); + if (lock_dropped && vmf->flags & FAULT_FLAG_VMA_LOCK) + return VM_FAULT_VMA_UNLOCKED | VM_FAULT_RETRY; return VM_FAULT_RETRY; } mmu_notifier_range_init_owner(&range, MMU_NOTIFY_EXCLUSIVE, 0, @@ -3704,7 +3707,8 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) bool exclusive = false; swp_entry_t entry; pte_t pte; - int locked; + bool locked; + bool lock_dropped; vm_fault_t ret = 0; void *shadow = NULL; @@ -3837,9 +3841,10 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) goto out_release; } - locked = folio_lock_or_retry(folio, vma->vm_mm, vmf->flags); - + locked = folio_lock_or_retry(folio, vma, vmf->flags, &lock_dropped); if (!locked) { + if (lock_dropped && vmf->flags & FAULT_FLAG_VMA_LOCK) + ret |= VM_FAULT_VMA_UNLOCKED; ret |= VM_FAULT_RETRY; goto out_release; } -- 2.40.1.495.gc816e09b53d-goog