From patchwork Wed Jun 16 01:23:45 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Morton X-Patchwork-Id: 12323683 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 824B2C48BE8 for ; Wed, 16 Jun 2021 01:23:49 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 381F361369 for ; Wed, 16 Jun 2021 01:23:49 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 381F361369 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id D28246B007E; Tue, 15 Jun 2021 21:23:48 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id CB2596B0080; Tue, 15 Jun 2021 21:23:48 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B2C276B0081; Tue, 15 Jun 2021 21:23:48 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0142.hostedemail.com [216.40.44.142]) by kanga.kvack.org (Postfix) with ESMTP id 7FFDE6B007E for ; Tue, 15 Jun 2021 21:23:48 -0400 (EDT) Received: from smtpin39.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 22A318249980 for ; Wed, 16 Jun 2021 01:23:48 +0000 (UTC) X-FDA: 78257840136.39.55FD384 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf20.hostedemail.com (Postfix) with ESMTP id 2366AFF for ; Wed, 16 Jun 2021 01:23:35 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id 4DAFA6137D; Wed, 16 Jun 2021 01:23:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1623806626; bh=yjKv8lvAh6d/PrfDR8Yktv3L+e2fvd1p3HqAx7amSsU=; h=Date:From:To:Subject:In-Reply-To:From; b=LOHm8+4OEE42rzNArFgmnA+veKuUaYZ7uhgGaFZ7LNHL0zyDv1cAGO44HETRfFGcJ t9SE97wNrscV5R2iBeUEg1KKWtfjrfGEsZj4Y9hj2h1PZjUkcJ30Oh/r0N1QRxPxhT LcrpYCdO9ohXTW2r7gjLfa77bTZKdlr6uGk0BFbY= Date: Tue, 15 Jun 2021 18:23:45 -0700 From: Andrew Morton To: akpm@linux-foundation.org, apopple@nvidia.com, hughd@google.com, jack@suse.cz, juew@google.com, kirill.shutemov@linux.intel.com, linmiaohe@huawei.com, linux-mm@kvack.org, minchan@kernel.org, mm-commits@vger.kernel.org, naoya.horiguchi@nec.com, osalvador@suse.de, peterx@redhat.com, rcampbell@nvidia.com, shakeelb@google.com, shy828301@gmail.com, stable@vger.kernel.org, torvalds@linux-foundation.org, wangyugui@e16-tech.com, willy@infradead.org, ziy@nvidia.com Subject: [patch 11/18] mm/thp: fix __split_huge_pmd_locked() on shmem migration entry Message-ID: <20210616012345.5wSsteRFU%akpm@linux-foundation.org> In-Reply-To: <20210615182248.9a0ba90e8e66b9f4a53c0d23@linux-foundation.org> User-Agent: s-nail v14.8.16 Authentication-Results: imf20.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=LOHm8+4O; dmarc=none; spf=pass (imf20.hostedemail.com: domain of akpm@linux-foundation.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org X-Stat-Signature: 3rsitzmhc34f4aibooc9hj1ajp3hwq9k X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 2366AFF X-HE-Tag: 1623806615-755391 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: From: Hugh Dickins Subject: mm/thp: fix __split_huge_pmd_locked() on shmem migration entry Patch series "mm/thp: fix THP splitting unmap BUGs and related", v10. Here is v2 batch of long-standing THP bug fixes that I had not got around to sending before, but prompted now by Wang Yugui's report https://lore.kernel.org/linux-mm/20210412180659.B9E3.409509F4@e16-tech.com/ Wang Yugui has tested a rollup of these fixes applied to 5.10.39, and they have done no harm, but have *not* fixed that issue: something more is needed and I have no idea of what. This patch (of 7): Stressing huge tmpfs page migration racing hole punch often crashed on the VM_BUG_ON(!pmd_present) in pmdp_huge_clear_flush(), with DEBUG_VM=y kernel; or shortly afterwards, on a bad dereference in __split_huge_pmd_locked() when DEBUG_VM=n. They forgot to allow for pmd migration entries in the non-anonymous case. Full disclosure: those particular experiments were on a kernel with more relaxed mmap_lock and i_mmap_rwsem locking, and were not repeated on the vanilla kernel: it is conceivable that stricter locking happens to avoid those cases, or makes them less likely; but __split_huge_pmd_locked() already allowed for pmd migration entries when handling anonymous THPs, so this commit brings the shmem and file THP handling into line. And while there: use old_pmd rather than _pmd, as in the following blocks; and make it clearer to the eye that the !vma_is_anonymous() block is self-contained, making an early return after accounting for unmapping. Link: https://lkml.kernel.org/r/af88612-1473-2eaa-903-8d1a448b26@google.com Link: https://lkml.kernel.org/r/dd221a99-efb3-cd1d-6256-7e646af29314@google.com Fixes: e71769ae5260 ("mm: enable thp migration for shmem thp") Signed-off-by: Hugh Dickins Cc: Kirill A. Shutemov Cc: Yang Shi Cc: Wang Yugui Cc: "Matthew Wilcox (Oracle)" Cc: Naoya Horiguchi Cc: Alistair Popple Cc: Ralph Campbell Cc: Zi Yan Cc: Miaohe Lin Cc: Minchan Kim Cc: Jue Wang Cc: Peter Xu Cc: Jan Kara Cc: Shakeel Butt Cc: Oscar Salvador Cc: Signed-off-by: Andrew Morton --- mm/huge_memory.c | 27 ++++++++++++++++++--------- mm/pgtable-generic.c | 5 ++--- 2 files changed, 20 insertions(+), 12 deletions(-) --- a/mm/huge_memory.c~mm-thp-fix-__split_huge_pmd_locked-on-shmem-migration-entry +++ a/mm/huge_memory.c @@ -2044,7 +2044,7 @@ static void __split_huge_pmd_locked(stru count_vm_event(THP_SPLIT_PMD); if (!vma_is_anonymous(vma)) { - _pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd); + old_pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd); /* * We are going to unmap this huge page. So * just go ahead and zap it @@ -2053,16 +2053,25 @@ static void __split_huge_pmd_locked(stru zap_deposited_table(mm, pmd); if (vma_is_special_huge(vma)) return; - page = pmd_page(_pmd); - if (!PageDirty(page) && pmd_dirty(_pmd)) - set_page_dirty(page); - if (!PageReferenced(page) && pmd_young(_pmd)) - SetPageReferenced(page); - page_remove_rmap(page, true); - put_page(page); + if (unlikely(is_pmd_migration_entry(old_pmd))) { + swp_entry_t entry; + + entry = pmd_to_swp_entry(old_pmd); + page = migration_entry_to_page(entry); + } else { + page = pmd_page(old_pmd); + if (!PageDirty(page) && pmd_dirty(old_pmd)) + set_page_dirty(page); + if (!PageReferenced(page) && pmd_young(old_pmd)) + SetPageReferenced(page); + page_remove_rmap(page, true); + put_page(page); + } add_mm_counter(mm, mm_counter_file(page), -HPAGE_PMD_NR); return; - } else if (pmd_trans_huge(*pmd) && is_huge_zero_pmd(*pmd)) { + } + + if (pmd_trans_huge(*pmd) && is_huge_zero_pmd(*pmd)) { /* * FIXME: Do we want to invalidate secondary mmu by calling * mmu_notifier_invalidate_range() see comments below inside --- a/mm/pgtable-generic.c~mm-thp-fix-__split_huge_pmd_locked-on-shmem-migration-entry +++ a/mm/pgtable-generic.c @@ -135,9 +135,8 @@ pmd_t pmdp_huge_clear_flush(struct vm_ar { pmd_t pmd; VM_BUG_ON(address & ~HPAGE_PMD_MASK); - VM_BUG_ON(!pmd_present(*pmdp)); - /* Below assumes pmd_present() is true */ - VM_BUG_ON(!pmd_trans_huge(*pmdp) && !pmd_devmap(*pmdp)); + VM_BUG_ON(pmd_present(*pmdp) && !pmd_trans_huge(*pmdp) && + !pmd_devmap(*pmdp)); pmd = pmdp_huge_get_and_clear(vma->vm_mm, address, pmdp); flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE); return pmd;