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 7E83FEE49B4 for ; Thu, 24 Aug 2023 23:22:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237741AbjHXXVt (ORCPT ); Thu, 24 Aug 2023 19:21:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58716 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235897AbjHXXVM (ORCPT ); Thu, 24 Aug 2023 19:21:12 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 909B2A1 for ; Thu, 24 Aug 2023 16:21:09 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 296A164AEE for ; Thu, 24 Aug 2023 23:21:09 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 76253C433C8; Thu, 24 Aug 2023 23:21:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1692919268; bh=F4dhQOuCeeoOV0D/V/WxOgY6z4UWx7+Xxt2r+lG3MK4=; h=Date:To:From:Subject:From; b=KHqjAd+hAd11M6pf/nydQnQMDNJZZtM1ckRi4y8Am1mYLEqZN4UaL6xcpTl8Fa8O5 hQg1WpKYpE87sxU0anNpUu0eFUPBvQhtZPx3U7RnF0AqHkEsvQTYj1vC+F9sz6QWq+ zP4HZ279aWvKFLh/bL1oqX4DtaqJVci25TFhljlo= Date: Thu, 24 Aug 2023 16:21:07 -0700 To: mm-commits@vger.kernel.org, yuzhao@google.com, ying.huang@intel.com, willy@infradead.org, viro@zeniv.linux.org.uk, vbabka@suse.cz, punit.agrawal@bytedance.com, peterx@redhat.com, pasha.tatashin@soleen.com, minchan@google.com, michel@lespinasse.org, mhocko@suse.com, lstoakes@gmail.com, Liam.Howlett@oracle.com, ldufour@linux.ibm.com, josef@toxicpanda.com, jack@suse.cz, hughd@google.com, hdanton@sina.com, hch@lst.de, hannes@cmpxchg.org, dhowells@redhat.com, david@redhat.com, dave@stgolabs.net, brauner@kernel.org, apopple@nvidia.com, surenb@google.com, akpm@linux-foundation.org From: Andrew Morton Subject: [merged mm-stable] mm-handle-swap-page-faults-under-per-vma-lock.patch removed from -mm tree Message-Id: <20230824232108.76253C433C8@smtp.kernel.org> Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org The quilt patch titled Subject: mm: handle swap page faults under per-VMA lock has been removed from the -mm tree. Its filename was mm-handle-swap-page-faults-under-per-vma-lock.patch This patch was dropped because it was merged into the mm-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm ------------------------------------------------------ From: Suren Baghdasaryan Subject: mm: handle swap page faults under per-VMA lock Date: Fri, 30 Jun 2023 14:19:56 -0700 When page fault is handled under per-VMA lock protection, all swap page faults are retried with mmap_lock because folio_lock_or_retry has to drop and reacquire mmap_lock if folio could not be immediately locked. Follow the same pattern as mmap_lock to drop per-VMA lock when waiting for folio and retrying once folio is available. With this obstacle removed, enable do_swap_page to operate under per-VMA lock protection. Drivers implementing ops->migrate_to_ram might still rely on mmap_lock, therefore we have to fall back to mmap_lock in that particular case. 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. Link: https://lkml.kernel.org/r/20230630211957.1341547-6-surenb@google.com Signed-off-by: Suren Baghdasaryan Tested-by: Alistair Popple Reviewed-by: Alistair Popple Acked-by: Peter Xu Cc: Al Viro Cc: Christian Brauner Cc: Christoph Hellwig Cc: David Hildenbrand Cc: David Howells Cc: Davidlohr Bueso Cc: Hillf Danton Cc: "Huang, Ying" Cc: Hugh Dickins Cc: Jan Kara Cc: Johannes Weiner Cc: Josef Bacik Cc: Laurent Dufour Cc: Liam R. Howlett Cc: Lorenzo Stoakes Cc: Matthew Wilcox Cc: Michal Hocko Cc: Michel Lespinasse Cc: Minchan Kim Cc: Pavel Tatashin Cc: Punit Agrawal Cc: Vlastimil Babka Cc: Yu Zhao Signed-off-by: Andrew Morton --- include/linux/mm.h | 13 +++++++++++++ mm/filemap.c | 17 ++++++++--------- mm/memory.c | 16 ++++++++++------ 3 files changed, 31 insertions(+), 15 deletions(-) --- a/include/linux/mm.h~mm-handle-swap-page-faults-under-per-vma-lock +++ a/include/linux/mm.h @@ -729,6 +729,14 @@ static inline void vma_mark_detached(str vma->detached = detached; } +static inline void release_fault_lock(struct vm_fault *vmf) +{ + if (vmf->flags & FAULT_FLAG_VMA_LOCK) + vma_end_read(vmf->vma); + else + mmap_read_unlock(vmf->vma->vm_mm); +} + struct vm_area_struct *lock_vma_under_rcu(struct mm_struct *mm, unsigned long address); @@ -749,6 +757,11 @@ static inline struct vm_area_struct *loc return NULL; } +static inline void release_fault_lock(struct vm_fault *vmf) +{ + mmap_read_unlock(vmf->vma->vm_mm); +} + #endif /* CONFIG_PER_VMA_LOCK */ extern const struct vm_operations_struct vma_dummy_vm_ops; --- a/mm/filemap.c~mm-handle-swap-page-faults-under-per-vma-lock +++ a/mm/filemap.c @@ -1671,27 +1671,26 @@ static int __folio_lock_async(struct fol * Return values: * 0 - folio is locked. * non-zero - 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. + * mmap_lock or per-VMA lock has been released (mmap_read_unlock() or + * vma_end_read()), unless flags had both FAULT_FLAG_ALLOW_RETRY and + * FAULT_FLAG_RETRY_NOWAIT set, in which case the lock is still held. * * If neither ALLOW_RETRY nor KILLABLE are set, will always return 0 - * with the folio locked and the mmap_lock unperturbed. + * with the folio locked and the mmap_lock/per-VMA lock is left unperturbed. */ vm_fault_t __folio_lock_or_retry(struct folio *folio, struct vm_fault *vmf) { - struct mm_struct *mm = vmf->vma->vm_mm; unsigned int flags = vmf->flags; if (fault_flag_allow_retry_first(flags)) { /* - * CAUTION! In this case, mmap_lock is not released - * even though return VM_FAULT_RETRY. + * CAUTION! In this case, mmap_lock/per-VMA lock is not + * released even though returning VM_FAULT_RETRY. */ if (flags & FAULT_FLAG_RETRY_NOWAIT) return VM_FAULT_RETRY; - mmap_read_unlock(mm); + release_fault_lock(vmf); if (flags & FAULT_FLAG_KILLABLE) folio_wait_locked_killable(folio); else @@ -1703,7 +1702,7 @@ vm_fault_t __folio_lock_or_retry(struct ret = __folio_lock_killable(folio); if (ret) { - mmap_read_unlock(mm); + release_fault_lock(vmf); return VM_FAULT_RETRY; } } else { --- a/mm/memory.c~mm-handle-swap-page-faults-under-per-vma-lock +++ a/mm/memory.c @@ -3746,12 +3746,6 @@ vm_fault_t do_swap_page(struct vm_fault if (!pte_unmap_same(vmf)) goto out; - if (vmf->flags & FAULT_FLAG_VMA_LOCK) { - ret = VM_FAULT_RETRY; - vma_end_read(vma); - goto out; - } - entry = pte_to_swp_entry(vmf->orig_pte); if (unlikely(non_swap_entry(entry))) { if (is_migration_entry(entry)) { @@ -3761,6 +3755,16 @@ vm_fault_t do_swap_page(struct vm_fault 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. + */ + vma_end_read(vma); + 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); _ Patches currently in -mm which might be from surenb@google.com are