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[2620:137:e000::1:20]) by mx.google.com with ESMTP id e189-20020a6369c6000000b0054405fa924fsi1764812pgc.891.2023.06.08.17.53.34; Thu, 08 Jun 2023 17:53:48 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20221208 header.b=IyAXoXjV; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237146AbjFIAwM (ORCPT + 99 others); Thu, 8 Jun 2023 20:52:12 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51630 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236404AbjFIAwH (ORCPT ); Thu, 8 Jun 2023 20:52:07 -0400 Received: from mail-yw1-x1149.google.com (mail-yw1-x1149.google.com [IPv6:2607:f8b0:4864:20::1149]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4E4C31FDF for ; Thu, 8 Jun 2023 17:52:06 -0700 (PDT) Received: by mail-yw1-x1149.google.com with SMTP id 00721157ae682-568960f4596so16974237b3.1 for ; Thu, 08 Jun 2023 17:52:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1686271925; x=1688863925; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=yuiOMQ0aSy0KwUuwsgymDjnxP8/lpeb7/V1M3j1Xb1E=; b=IyAXoXjV7xCg1A6CTIB0VVGoVOFSNHNynjRms7ZT4ZJuasxkgD/xINqmOy3R2QWmj6 LweWil7YBo9DB23KcYDwjIFg2tzhu/sNAVap1M78azP9/yh5rbc8NVuFliEYHm7NBXMo soQpcPklJ87/HIwm9iXTXt6sGz2j9ugeHoaBCIPXu786yDSkXPG2N+lpjRD03pJqKf4U ynS64LhxDlPhl3xfkAFkbEO/hQz6xagu8ZpHoJtj8fgQugYSIR8+59/FTuzy8cFImM2J 9Fgql8U7ice3Cs5matPGhf41n4PEh7vFyVlNzgNeB1JUE14tptvSHOdWg+sF+J8fGOVy muaA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1686271925; x=1688863925; 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=yuiOMQ0aSy0KwUuwsgymDjnxP8/lpeb7/V1M3j1Xb1E=; b=lsMU9RM6oDJbviGoQqOnTv5JR0Obnwvn+GkhndVfPScSpkY3ZR84zH0vRxdpSoAvE6 jdgO4kKvi0rCIiJiqakpasTbR1TcXTuDsVDjC41gENd6lr1b6oZ1oKPvmc7SGN2SFtdY nbda6kfgovLgviDwEIejZAUH7HmVvBZhCtxooOvKY1OEVTd8iEjl1dWlbTP44ZGJLee2 bVfkqaK+2eV8xza8JKkRKHneJA+zn9ESSJ+v8mVR2x1uMNH9WWBPf4QKXkrBD6P0XDdp UTsymvHgLtY7WFKQso5AthBM8Jpe+Mv8doE2iuzg0arpw+9Fc1YtQEGGu+zK/3H3J/pl Iuqw== X-Gm-Message-State: AC+VfDyyj822LeYz2bBk4yXhezGiq8Uk66hOv6OirgMm+rh83EL95t+I Uphmpjh7/m/W3ZUZvF3bz3ms8zpuL0U= X-Received: from surenb-desktop.mtv.corp.google.com ([2620:15c:211:201:c03e:d3b7:767a:9467]) (user=surenb job=sendgmr) by 2002:a81:b2c9:0:b0:55d:8472:4597 with SMTP id q192-20020a81b2c9000000b0055d84724597mr729567ywh.10.1686271925574; Thu, 08 Jun 2023 17:52:05 -0700 (PDT) Date: Thu, 8 Jun 2023 17:51:53 -0700 In-Reply-To: <20230609005158.2421285-1-surenb@google.com> Mime-Version: 1.0 References: <20230609005158.2421285-1-surenb@google.com> X-Mailer: git-send-email 2.41.0.162.gfafddb0af9-goog Message-ID: <20230609005158.2421285-2-surenb@google.com> Subject: [PATCH v2 1/6] swap: remove remnants of polling from read_swap_cache_async 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, peterx@redhat.com, ying.huang@intel.com, david@redhat.com, yuzhao@google.com, dhowells@redhat.com, hughd@google.com, viro@zeniv.linux.org.uk, brauner@kernel.org, pasha.tatashin@soleen.com, surenb@google.com, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@android.com X-Spam-Status: No, score=-9.6 required=5.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE, SPF_HELO_NONE,SPF_PASS,T_SCC_BODY_TEXT_LINE,USER_IN_DEF_DKIM_WL autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1768184378353414387?= X-GMAIL-MSGID: =?utf-8?q?1768184378353414387?= Commit [1] introduced IO polling support during swapin to reduce swap read latency for block devices that can be polled. However later commit [2] removed polling support. Therefore it seems safe to remove do_poll parameter in read_swap_cache_async and always call swap_readpage with synchronous=false waiting for IO completion in folio_lock_or_retry. [1] commit 23955622ff8d ("swap: add block io poll in swapin path") [2] commit 9650b453a3d4 ("block: ignore RWF_HIPRI hint for sync dio") Suggested-by: Huang Ying Signed-off-by: Suren Baghdasaryan Reviewed-by: "Huang, Ying" Reviewed-by: Christoph Hellwig --- mm/madvise.c | 4 ++-- mm/swap.h | 1 - mm/swap_state.c | 12 +++++------- 3 files changed, 7 insertions(+), 10 deletions(-) diff --git a/mm/madvise.c b/mm/madvise.c index b5ffbaf616f5..b1e8adf1234e 100644 --- a/mm/madvise.c +++ b/mm/madvise.c @@ -215,7 +215,7 @@ static int swapin_walk_pmd_entry(pmd_t *pmd, unsigned long start, continue; page = read_swap_cache_async(entry, GFP_HIGHUSER_MOVABLE, - vma, index, false, &splug); + vma, index, &splug); if (page) put_page(page); } @@ -252,7 +252,7 @@ static void force_shm_swapin_readahead(struct vm_area_struct *vma, rcu_read_unlock(); page = read_swap_cache_async(swap, GFP_HIGHUSER_MOVABLE, - NULL, 0, false, &splug); + NULL, 0, &splug); if (page) put_page(page); diff --git a/mm/swap.h b/mm/swap.h index 7c033d793f15..8a3c7a0ace4f 100644 --- a/mm/swap.h +++ b/mm/swap.h @@ -46,7 +46,6 @@ struct folio *filemap_get_incore_folio(struct address_space *mapping, struct page *read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask, struct vm_area_struct *vma, unsigned long addr, - bool do_poll, struct swap_iocb **plug); struct page *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask, struct vm_area_struct *vma, diff --git a/mm/swap_state.c b/mm/swap_state.c index b76a65ac28b3..a3839de71f3f 100644 --- a/mm/swap_state.c +++ b/mm/swap_state.c @@ -517,15 +517,14 @@ struct page *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask, */ struct page *read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask, struct vm_area_struct *vma, - unsigned long addr, bool do_poll, - struct swap_iocb **plug) + unsigned long addr, struct swap_iocb **plug) { bool page_was_allocated; struct page *retpage = __read_swap_cache_async(entry, gfp_mask, vma, addr, &page_was_allocated); if (page_was_allocated) - swap_readpage(retpage, do_poll, plug); + swap_readpage(retpage, false, plug); return retpage; } @@ -620,7 +619,7 @@ struct page *swap_cluster_readahead(swp_entry_t entry, gfp_t gfp_mask, struct swap_info_struct *si = swp_swap_info(entry); struct blk_plug plug; struct swap_iocb *splug = NULL; - bool do_poll = true, page_allocated; + bool page_allocated; struct vm_area_struct *vma = vmf->vma; unsigned long addr = vmf->address; @@ -628,7 +627,6 @@ struct page *swap_cluster_readahead(swp_entry_t entry, gfp_t gfp_mask, if (!mask) goto skip; - do_poll = false; /* Read a page_cluster sized and aligned cluster around offset. */ start_offset = offset & ~mask; end_offset = offset | mask; @@ -660,7 +658,7 @@ struct page *swap_cluster_readahead(swp_entry_t entry, gfp_t gfp_mask, lru_add_drain(); /* Push any new pages onto the LRU now */ skip: /* The page was likely read above, so no need for plugging here */ - return read_swap_cache_async(entry, gfp_mask, vma, addr, do_poll, NULL); + return read_swap_cache_async(entry, gfp_mask, vma, addr, NULL); } int init_swap_address_space(unsigned int type, unsigned long nr_pages) @@ -825,7 +823,7 @@ static struct page *swap_vma_readahead(swp_entry_t fentry, gfp_t gfp_mask, skip: /* The page was likely read above, so no need for plugging here */ return read_swap_cache_async(fentry, gfp_mask, vma, vmf->address, - ra_info.win == 1, NULL); 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Instead of retrying all swapped page faults, retry only when folio locking fails. Note that the only time do_swap_page calls synchronous swap_readpage is when SWP_SYNCHRONOUS_IO is set, which is only set for QUEUE_FLAG_SYNCHRONOUS devices: brd, zram and nvdimms (both btt and pmem). Therefore we don't sleep in this path, and there's no need to drop the mmap or per-vma lock. Drivers implementing ops->migrate_to_ram might still rely on mmap_lock, therefore fall back to mmap_lock in this case. Signed-off-by: Suren Baghdasaryan --- mm/filemap.c | 6 ++++++ mm/memory.c | 14 +++++++++----- 2 files changed, 15 insertions(+), 5 deletions(-) diff --git a/mm/filemap.c b/mm/filemap.c index b4c9bd368b7e..7cb0a3776a07 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -1706,6 +1706,8 @@ static int __folio_lock_async(struct folio *folio, struct wait_page_queue *wait) * 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. * * If neither ALLOW_RETRY nor KILLABLE are set, will always return true * with the folio locked and the mmap_lock unperturbed. @@ -1713,6 +1715,10 @@ static int __folio_lock_async(struct folio *folio, struct wait_page_queue *wait) bool __folio_lock_or_retry(struct folio *folio, struct mm_struct *mm, unsigned int flags) { + /* 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 diff --git a/mm/memory.c b/mm/memory.c index f69fbc251198..41f45819a923 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3711,11 +3711,6 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) if (!pte_unmap_same(vmf)) goto out; - if (vmf->flags & FAULT_FLAG_VMA_LOCK) { - ret = VM_FAULT_RETRY; - goto out; - } - entry = pte_to_swp_entry(vmf->orig_pte); if (unlikely(non_swap_entry(entry))) { if (is_migration_entry(entry)) { @@ -3725,6 +3720,15 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) vmf->page = pfn_swap_entry_to_page(entry); ret = remove_device_exclusive_entry(vmf); } else if (is_device_private_entry(entry)) { + if (vmf->flags & FAULT_FLAG_VMA_LOCK) { + /* + * migrate_to_ram is not yet ready to operate + * under VMA lock. + */ + ret |= VM_FAULT_RETRY; + goto out; + } + vmf->page = pfn_swap_entry_to_page(entry); vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address, &vmf->ptl); From patchwork Fri Jun 9 00:51:55 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Suren Baghdasaryan X-Patchwork-Id: 105191 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a59:994d:0:b0:3d9:f83d:47d9 with SMTP id k13csp638051vqr; Thu, 8 Jun 2023 18:00:19 -0700 (PDT) X-Google-Smtp-Source: ACHHUZ5zgvkFB+F88mY7mcMuOxgxZh3Gq779O3VJoNihSKdFEBdow11ST5XnJVEyZmSdgVpfzneI X-Received: by 2002:a05:6358:4fa0:b0:129:cc31:73e0 with SMTP id cg32-20020a0563584fa000b00129cc3173e0mr6847931rwb.19.1686272419288; Thu, 08 Jun 2023 18:00:19 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1686272419; cv=none; d=google.com; s=arc-20160816; b=CaVAKhkh6qPdLzu4CPDrU+RXXr5vlHVQHohZZ+aFPkur2R5GgQgSDutDHARMrdwZf0 nSOxHEEN7HAPMjN4OhUV0BRIGnVmAv8EUmR1v5hqKnG3uHQO7EvkhbLjJ2Vs+xmauRhy FkYfhLN6Nsa1n3b04bbVDOaz58r0ZGFN01O6oP/pZUuA38t71t7W/z85UIQkaqiV8Krd bZvSnb1L5DEacJ9WfUSM8JOwWovYOroiY/m/y44771lGiCFM2EpzRWEc6KQd5DdCKWGI EMXFMrXzc/ayoFmXthjDru+64hXkv9zIT4vCuVwUekaVDy/5BKpmmxb9s+sScXLOx87g j30w== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:cc:to:from:subject:message-id:references :mime-version:in-reply-to:date:dkim-signature; bh=JqcDdPqSbAUSGbTjmvLRcpjiA0c+o9DbrViIiTIy+Ug=; b=m17jMrxC1dn4o2Q+e0KlWpyd72kUEKq4faD+Y/tCSYvtkQAPdcjRkV/cUx+zaAN+7f BKBJ5CdAdRorOCZNed/kgLeVBkPN5aaWWjipSzI9E83Z+tlHTB32BpFTQW9yO7pZzzj8 Us61Ep9CV4gW5oMozLet32gwkEINAwCapmpn7q15tzkEAFN6MPlbUPRBpwAoexR2AAbl aDSylx1b+E3eYi6HlL+6z5oqqVOQ28SOS0WlKsXzbkdnJiU0YXL/SUXkXgZsmfzbOo2Y bZ85ESCMu2EUvaZvk3Bp5fS0L6Ffy3Gx3sRUCiyhhjm3jPn2rdA2VV8puo6HA4zyVaYN MeFA== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@google.com header.s=20221208 header.b="zXF0/SOz"; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com Received: from out1.vger.email (out1.vger.email. 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The element for VM_FAULT_COMPLETED is missing, add it. Signed-off-by: Suren Baghdasaryan Reviewed-by: Peter Xu --- include/linux/mm_types.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 306a3d1a0fa6..79765e3dd8f3 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -1070,7 +1070,8 @@ enum vm_fault_reason { { VM_FAULT_RETRY, "RETRY" }, \ { VM_FAULT_FALLBACK, "FALLBACK" }, \ { VM_FAULT_DONE_COW, "DONE_COW" }, \ - { VM_FAULT_NEEDDSYNC, "NEEDDSYNC" } + { VM_FAULT_NEEDDSYNC, "NEEDDSYNC" }, \ + { VM_FAULT_COMPLETED, "COMPLETED" } struct vm_special_mapping { const char *name; /* The name, e.g. "[vdso]". */ From patchwork Fri Jun 9 00:51:56 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Suren Baghdasaryan X-Patchwork-Id: 105192 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a59:994d:0:b0:3d9:f83d:47d9 with SMTP id k13csp638049vqr; Thu, 8 Jun 2023 18:00:19 -0700 (PDT) X-Google-Smtp-Source: ACHHUZ5R+8yTCSv2Zxox/UZXEYu1ASNlM5o40S2KFyy6bsal3NQ95pIVMROwtwaHmWqxjMLjQ9SC X-Received: by 2002:a05:6358:baa2:b0:129:ca25:6486 with SMTP id dg34-20020a056358baa200b00129ca256486mr4704600rwb.29.1686272419152; Thu, 08 Jun 2023 18:00:19 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1686272419; cv=none; d=google.com; s=arc-20160816; b=wMLlYwvkJ6Ks0E+oDUPzYe2TvUWPjBG34lgFSk/viGl9v4pTR9TDVDmm34gb91dr6y xFe+fLTpsLTifzVwafBUI8L9TpvMpSLx7EspSn3dT+yEzVQGTzmrSaUxVvTa3cx4yOH9 X/8iW18y+1Qr/mm11HH+fEH7yFNApVmT13cet4JLlcyq0Ql0pqc+aICjHplMVa+uyXhz 0iVQRkychEbXWfx4FcdnZ1HN1ffqAdWHCVMyV1swjvrrElpYZg2h1nBgLXsUjlnP4upU 3EKm3x9lfbGKiSf0wIDUm/etCBt93f0JC8Mt9GkPOkhJLDgfUhwGgvOmAlwvnZisSF7o FvXQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:cc:to:from:subject:message-id:references :mime-version:in-reply-to:date:dkim-signature; bh=uuo3Il/2NbgOWAM0rjqTihVZSZhUnoZMQ/ESG1PbGOc=; b=bJi7Dg1d4BcVjulkY4Q7DaVp5UOEfG9xunSpA4g3E7KoAYivkm+j0AGwERjKk1Lo5Y TWppBVsXDQqD6Ci3MlrBjz2/cWJwM9Bv+eeL651BDh/xFGSTVi62dIc64HYNjPfYw53+ dZkYC1w9TtNESRtNP7W7QI4zMvw/4XJraH/OfD5ZvdEN+kcw/f4lW6u6YloOHnMFM3aP A1iqxqokYvGO5hJNh9JlqOleU43YozlR4J7O+QShWVpLZIWIbmKTSmhtBt8uX0DpAQhg wyo4z9wrUB66B8V84pHuNDEWOxwY8z/BkV70MAUiZ+tAW65kdeSxHkXQ0u4Lv1w8Qz1r hL7Q== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@google.com header.s=20221208 header.b=aoHc7JPC; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com Received: from out1.vger.email (out1.vger.email. [2620:137:e000::1:20]) by mx.google.com with ESMTP id q2-20020a637502000000b0053f33ec5635si1813757pgc.865.2023.06.08.18.00.06; Thu, 08 Jun 2023 18:00:19 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20221208 header.b=aoHc7JPC; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229661AbjFIAwh (ORCPT + 99 others); Thu, 8 Jun 2023 20:52:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51726 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234892AbjFIAwO (ORCPT ); Thu, 8 Jun 2023 20:52:14 -0400 Received: from mail-pg1-x54a.google.com (mail-pg1-x54a.google.com [IPv6:2607:f8b0:4864:20::54a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C68AC2685 for ; Thu, 8 Jun 2023 17:52:12 -0700 (PDT) Received: by mail-pg1-x54a.google.com with SMTP id 41be03b00d2f7-53b9eb7bda0so220334a12.0 for ; Thu, 08 Jun 2023 17:52:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1686271932; x=1688863932; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=uuo3Il/2NbgOWAM0rjqTihVZSZhUnoZMQ/ESG1PbGOc=; b=aoHc7JPCZ32CAYt9q46WDYGEOxxS+8Zg8n+MkQ8tBFVy2AxaNM8+3Gds918auhPTHa q1i93JJIOBjYqWdat77Bw43ovYfILELgsQ3A15M4ncn74YtVwsuP81alu9yqHz/6QEf4 0ZCIwnE+WqrId9F8Np2B9UzySwNVPcW9qaPUxrGBEsK8nkCGUUE7v/JS22HdzPoOb4MB Chi4Dc24/vK44G+H3O7mb/dNtV3gVAS4dKZye3QS8d/JCKeQ8FR8f6Rt4chkxNrZVvil NBHO4/LslE98QkZt8lZcAJ+QXDZaDtGSI1vY2Loous6hPUzUbnAktXCDF6R5gPFfIwoD hcMw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1686271932; x=1688863932; 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=uuo3Il/2NbgOWAM0rjqTihVZSZhUnoZMQ/ESG1PbGOc=; b=W696qUNB0XBmguvWzibGh1+7V+4mPcC0oBIxXjHuCYY6D1P/iaEob+oQwyEqnNJK1g 0Zqr5AJlb2yOWOHKIUejie2Woq4h52fgBSoMPTySj1ZCRDTVL/zaDG/eyY/BmHXEM0gu kqSSXR9ohk6muSNs9oppWIVU14CflfpdV9nyuO+iGx+e0ENHt1eYWjJ+Usv7UklU0CNI U8aN11MIDeeWk1KXYOAu/cn10B2jkU2e3REG/3gRPkfkYVVG5y5sKL6l9xxFErZLriAy lvQwAiM5U68S8yivgpSGetwBJAhIpIt2H9CA8wn9/SCGb6RXJEhm0grSF7f6c+D+J81s J1/g== X-Gm-Message-State: AC+VfDw7AMq/UqIMU/CQtkye9W+oLEpgZJDAeVs4iiL5kKRM8aKXd+XZ ZGcMoJepZiCK1G7VutpyXz/VzcaZXSM= X-Received: from surenb-desktop.mtv.corp.google.com ([2620:15c:211:201:c03e:d3b7:767a:9467]) (user=surenb job=sendgmr) by 2002:a63:d44:0:b0:503:77c9:45aa with SMTP id 4-20020a630d44000000b0050377c945aamr225410pgn.9.1686271932107; Thu, 08 Jun 2023 17:52:12 -0700 (PDT) Date: Thu, 8 Jun 2023 17:51:56 -0700 In-Reply-To: <20230609005158.2421285-1-surenb@google.com> Mime-Version: 1.0 References: <20230609005158.2421285-1-surenb@google.com> X-Mailer: git-send-email 2.41.0.162.gfafddb0af9-goog Message-ID: <20230609005158.2421285-5-surenb@google.com> Subject: [PATCH v2 4/6] mm: drop VMA lock before waiting for migration 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, peterx@redhat.com, ying.huang@intel.com, david@redhat.com, yuzhao@google.com, dhowells@redhat.com, hughd@google.com, viro@zeniv.linux.org.uk, brauner@kernel.org, pasha.tatashin@soleen.com, surenb@google.com, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@android.com X-Spam-Status: No, score=-9.6 required=5.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE, SPF_HELO_NONE,SPF_PASS,T_SCC_BODY_TEXT_LINE,USER_IN_DEF_DKIM_WL autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1768184788353554269?= X-GMAIL-MSGID: =?utf-8?q?1768184788353554269?= migration_entry_wait does not need VMA lock, therefore it can be dropped before waiting. Introduce VM_FAULT_VMA_UNLOCKED to indicate that VMA lock was dropped while in handle_mm_fault(). Note that once VMA lock is dropped, the VMA reference can't be used as there are no guarantees it was not freed. Signed-off-by: Suren Baghdasaryan --- arch/arm64/mm/fault.c | 3 ++- arch/powerpc/mm/fault.c | 3 ++- arch/s390/mm/fault.c | 3 ++- arch/x86/mm/fault.c | 3 ++- include/linux/mm_types.h | 6 +++++- mm/memory.c | 12 ++++++++++-- 6 files changed, 23 insertions(+), 7 deletions(-) diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c index 6045a5117ac1..8f59badbffb5 100644 --- a/arch/arm64/mm/fault.c +++ b/arch/arm64/mm/fault.c @@ -601,7 +601,8 @@ static int __kprobes do_page_fault(unsigned long far, unsigned long esr, goto lock_mmap; } fault = handle_mm_fault(vma, addr, mm_flags | FAULT_FLAG_VMA_LOCK, regs); - vma_end_read(vma); + if (!(fault & VM_FAULT_VMA_UNLOCKED)) + vma_end_read(vma); if (!(fault & VM_FAULT_RETRY)) { count_vm_vma_lock_event(VMA_LOCK_SUCCESS); diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c index 531177a4ee08..b27730f07141 100644 --- a/arch/powerpc/mm/fault.c +++ b/arch/powerpc/mm/fault.c @@ -494,7 +494,8 @@ static int ___do_page_fault(struct pt_regs *regs, unsigned long address, } fault = handle_mm_fault(vma, address, flags | FAULT_FLAG_VMA_LOCK, regs); - vma_end_read(vma); + if (!(fault & VM_FAULT_VMA_UNLOCKED)) + vma_end_read(vma); if (!(fault & VM_FAULT_RETRY)) { count_vm_vma_lock_event(VMA_LOCK_SUCCESS); diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c index b65144c392b0..cc923dbb0821 100644 --- a/arch/s390/mm/fault.c +++ b/arch/s390/mm/fault.c @@ -418,7 +418,8 @@ static inline vm_fault_t do_exception(struct pt_regs *regs, int access) goto lock_mmap; } fault = handle_mm_fault(vma, address, flags | FAULT_FLAG_VMA_LOCK, regs); - vma_end_read(vma); + if (!(fault & VM_FAULT_VMA_UNLOCKED)) + vma_end_read(vma); if (!(fault & VM_FAULT_RETRY)) { count_vm_vma_lock_event(VMA_LOCK_SUCCESS); goto out; diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index e4399983c50c..ef62ab2fd211 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -1347,7 +1347,8 @@ void do_user_addr_fault(struct pt_regs *regs, goto lock_mmap; } fault = handle_mm_fault(vma, address, flags | FAULT_FLAG_VMA_LOCK, regs); - vma_end_read(vma); + if (!(fault & VM_FAULT_VMA_UNLOCKED)) + vma_end_read(vma); if (!(fault & VM_FAULT_RETRY)) { count_vm_vma_lock_event(VMA_LOCK_SUCCESS); diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 79765e3dd8f3..bd6b95c82f7a 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -1030,6 +1030,8 @@ typedef __bitwise unsigned int vm_fault_t; * fsync() to complete (for synchronous page faults * in DAX) * @VM_FAULT_COMPLETED: ->fault completed, meanwhile mmap lock released + * @VM_FAULT_VMA_UNLOCKED: VMA lock was released, vmf->vma should no longer + * be accessed * @VM_FAULT_HINDEX_MASK: mask HINDEX value * */ @@ -1047,6 +1049,7 @@ enum vm_fault_reason { VM_FAULT_DONE_COW = (__force vm_fault_t)0x001000, VM_FAULT_NEEDDSYNC = (__force vm_fault_t)0x002000, VM_FAULT_COMPLETED = (__force vm_fault_t)0x004000, + VM_FAULT_VMA_UNLOCKED = (__force vm_fault_t)0x008000, VM_FAULT_HINDEX_MASK = (__force vm_fault_t)0x0f0000, }; @@ -1071,7 +1074,8 @@ enum vm_fault_reason { { VM_FAULT_FALLBACK, "FALLBACK" }, \ { VM_FAULT_DONE_COW, "DONE_COW" }, \ { VM_FAULT_NEEDDSYNC, "NEEDDSYNC" }, \ - { VM_FAULT_COMPLETED, "COMPLETED" } + { VM_FAULT_COMPLETED, "COMPLETED" }, \ + { VM_FAULT_VMA_UNLOCKED, "VMA_UNLOCKED" } struct vm_special_mapping { const char *name; /* The name, e.g. "[vdso]". */ diff --git a/mm/memory.c b/mm/memory.c index 41f45819a923..c234f8085f1e 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3714,8 +3714,16 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) entry = pte_to_swp_entry(vmf->orig_pte); if (unlikely(non_swap_entry(entry))) { if (is_migration_entry(entry)) { - migration_entry_wait(vma->vm_mm, vmf->pmd, - vmf->address); + /* Save mm in case VMA lock is dropped */ + struct mm_struct *mm = vma->vm_mm; + + if (vmf->flags & FAULT_FLAG_VMA_LOCK) { + /* No need to hold VMA lock for migration */ + vma_end_read(vma); + /* WARNING: VMA can't be used after this */ + ret |= VM_FAULT_VMA_UNLOCKED; + } + migration_entry_wait(mm, vmf->pmd, vmf->address); } else if (is_device_exclusive_entry(entry)) { vmf->page = pfn_swap_entry_to_page(entry); ret = remove_device_exclusive_entry(vmf); From patchwork Fri Jun 9 00:51:57 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Suren Baghdasaryan X-Patchwork-Id: 105189 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a59:994d:0:b0:3d9:f83d:47d9 with SMTP id k13csp636236vqr; 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Signed-off-by: Suren Baghdasaryan --- include/linux/pagemap.h | 14 ++++++++++---- mm/filemap.c | 43 ++++++++++++++++++++++------------------- mm/memory.c | 13 ++++++++----- 3 files changed, 41 insertions(+), 29 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 7cb0a3776a07..838955635fbc 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 c234f8085f1e..acb09a3aad53 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 +3707,7 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) bool exclusive = false; swp_entry_t entry; pte_t pte; - int locked; + bool lock_dropped; vm_fault_t ret = 0; void *shadow = NULL; @@ -3837,9 +3840,9 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) goto out_release; } - locked = folio_lock_or_retry(folio, vma->vm_mm, vmf->flags); - - if (!locked) { + if (!folio_lock_or_retry(folio, vma, vmf->flags, &lock_dropped)) { + if (lock_dropped && vmf->flags & FAULT_FLAG_VMA_LOCK) + ret |= VM_FAULT_VMA_UNLOCKED; ret |= VM_FAULT_RETRY; goto out_release; } From patchwork Fri Jun 9 00:51:58 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Suren Baghdasaryan X-Patchwork-Id: 105193 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a59:994d:0:b0:3d9:f83d:47d9 with SMTP id k13csp638080vqr; Thu, 8 Jun 2023 18:00:23 -0700 (PDT) X-Google-Smtp-Source: ACHHUZ6ORD0HHaJQ4sf/JCuH1dXspnisgsQdggNimRHPnY9zksmFNuTeI1iY9xh++8TX6BojWiLY X-Received: by 2002:a05:6a20:258b:b0:106:5dff:5dc6 with SMTP id k11-20020a056a20258b00b001065dff5dc6mr10118682pzd.16.1686272423207; Thu, 08 Jun 2023 18:00:23 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1686272423; cv=none; d=google.com; s=arc-20160816; b=idX/9Vh8A3Nay6esCEw3NVsMQE22A6IIMNJMXlSyMOi9fMVEAwrt68D//ZWvDbVWdo mOlQ3fveouE6eZdSUY8vzlR4xv46FfqA/KhJlP4xVWrztR3ibEkApXklJWsHdVmVJGo2 zXIP6UJ85IisAzExo69upWk/YRd9UzGSbx3Vki7Gfi/x/w9wFQ8PI6sMbHup5mGr3o2Y 4ZRGDc2zzS6ZmS/vw/4BcCKBdeJboR6Oulx6dDRLPCteS6ySi+uw5lEkUi5KoglU/PdB lEgW+phvYScPUT4TyDnZkcqeH9MYVOxTgakf2//IOn7xJsn1QDn6yw0KkZGuzLNQU4O7 ywQg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:cc:to:from:subject:message-id:references :mime-version:in-reply-to:date:dkim-signature; bh=R1WyFySTZ0XkKYIf3B7+wOl2DNVNhKC+z/byy1yFxnw=; b=cr0/mtNaVjpGL2QfTAW1UDzP+i9zTTpdpWepBKR3CYKYN7LrKi2GkCC3Ax/GhAC0Xn NRYL5WMDiwJ/RDOCdnBR4PdVRfwDTyHrW+E2qOiYEFry8g6HVoiGVK1HM12STxqjAfab vL4I3kPP5+7uXiuK9GTjNsSg0sHfuEu5fcr1+GNE2dXskKEU4ceqSmIRNec4BWAFXNrf LdoURMt6wYYnPww/AMHisUbWxKDt7CaU9w9o8wJfASjfd0tfQjNpt9lVSKxAJLXpJUSW zeEc6h6ZqmqlxJJwFelS43dkDT34OeaN8rIuvi1KvVc1Xfqi36WsRfLsrv3cFZKanyvB k/nw== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@google.com header.s=20221208 header.b=4hO9nbpC; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com Received: from out1.vger.email (out1.vger.email. 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Signed-off-by: Suren Baghdasaryan --- fs/userfaultfd.c | 42 ++++++++++++++++++++++-------------------- mm/memory.c | 9 --------- 2 files changed, 22 insertions(+), 29 deletions(-) diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c index 0fd96d6e39ce..23c3a4ce45d9 100644 --- a/fs/userfaultfd.c +++ b/fs/userfaultfd.c @@ -277,17 +277,17 @@ static inline struct uffd_msg userfault_msg(unsigned long address, * hugepmd ranges. */ static inline bool userfaultfd_huge_must_wait(struct userfaultfd_ctx *ctx, - struct vm_area_struct *vma, - unsigned long address, - unsigned long flags, - unsigned long reason) + struct vm_fault *vmf, + unsigned long reason) { + struct vm_area_struct *vma = vmf->vma; pte_t *ptep, pte; bool ret = true; - mmap_assert_locked(ctx->mm); + if (!(vmf->flags & FAULT_FLAG_VMA_LOCK)) + mmap_assert_locked(ctx->mm); - ptep = hugetlb_walk(vma, address, vma_mmu_pagesize(vma)); + ptep = hugetlb_walk(vma, vmf->address, vma_mmu_pagesize(vma)); if (!ptep) goto out; @@ -308,10 +308,8 @@ static inline bool userfaultfd_huge_must_wait(struct userfaultfd_ctx *ctx, } #else static inline bool userfaultfd_huge_must_wait(struct userfaultfd_ctx *ctx, - struct vm_area_struct *vma, - unsigned long address, - unsigned long flags, - unsigned long reason) + struct vm_fault *vmf, + unsigned long reason) { return false; /* should never get here */ } @@ -325,11 +323,11 @@ static inline bool userfaultfd_huge_must_wait(struct userfaultfd_ctx *ctx, * threads. */ static inline bool userfaultfd_must_wait(struct userfaultfd_ctx *ctx, - unsigned long address, - unsigned long flags, + struct vm_fault *vmf, unsigned long reason) { struct mm_struct *mm = ctx->mm; + unsigned long address = vmf->address; pgd_t *pgd; p4d_t *p4d; pud_t *pud; @@ -337,7 +335,8 @@ static inline bool userfaultfd_must_wait(struct userfaultfd_ctx *ctx, pte_t *pte; bool ret = true; - mmap_assert_locked(mm); + if (!(vmf->flags & FAULT_FLAG_VMA_LOCK)) + mmap_assert_locked(mm); pgd = pgd_offset(mm, address); if (!pgd_present(*pgd)) @@ -445,7 +444,8 @@ vm_fault_t handle_userfault(struct vm_fault *vmf, unsigned long reason) * Coredumping runs without mmap_lock so we can only check that * the mmap_lock is held, if PF_DUMPCORE was not set. */ - mmap_assert_locked(mm); + if (!(vmf->flags & FAULT_FLAG_VMA_LOCK)) + mmap_assert_locked(mm); ctx = vma->vm_userfaultfd_ctx.ctx; if (!ctx) @@ -561,15 +561,17 @@ vm_fault_t handle_userfault(struct vm_fault *vmf, unsigned long reason) spin_unlock_irq(&ctx->fault_pending_wqh.lock); if (!is_vm_hugetlb_page(vma)) - must_wait = userfaultfd_must_wait(ctx, vmf->address, vmf->flags, - reason); + must_wait = userfaultfd_must_wait(ctx, vmf, reason); else - must_wait = userfaultfd_huge_must_wait(ctx, vma, - vmf->address, - vmf->flags, reason); + must_wait = userfaultfd_huge_must_wait(ctx, vmf, reason); if (is_vm_hugetlb_page(vma)) hugetlb_vma_unlock_read(vma); - mmap_read_unlock(mm); + if (vmf->flags & FAULT_FLAG_VMA_LOCK) { + vma_end_read(vma); + /* WARNING: VMA can't be used after this */ + ret |= VM_FAULT_VMA_UNLOCKED; + } else + mmap_read_unlock(mm); if (likely(must_wait && !READ_ONCE(ctx->released))) { wake_up_poll(&ctx->fd_wqh, EPOLLIN); diff --git a/mm/memory.c b/mm/memory.c index acb09a3aad53..b2ea015dcb87 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -5306,15 +5306,6 @@ struct vm_area_struct *lock_vma_under_rcu(struct mm_struct *mm, if (!vma_start_read(vma)) goto inval; - /* - * Due to the possibility of userfault handler dropping mmap_lock, avoid - * it for now and fall back to page fault handling under mmap_lock. - */ - if (userfaultfd_armed(vma)) { - vma_end_read(vma); - goto inval; - } - /* Check since vm_start/vm_end might change before we lock the VMA */ if (unlikely(address < vma->vm_start || address >= vma->vm_end)) { vma_end_read(vma);