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 11E58C54E76 for ; Thu, 5 Jan 2023 01:47:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229447AbjAEBrT (ORCPT ); Wed, 4 Jan 2023 20:47:19 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36160 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229787AbjAEBqy (ORCPT ); Wed, 4 Jan 2023 20:46:54 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8E7BD2F786 for ; Wed, 4 Jan 2023 17:46:53 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 2AD7C618BB for ; Thu, 5 Jan 2023 01:46:53 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7C908C433F0; Thu, 5 Jan 2023 01:46:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1672883212; bh=oacNmnBnhNdb6kxTgCIOvvet4EFRozABT4VV+ArIKu4=; h=Date:To:From:Subject:From; b=AsGE52LAwpGASg6oCzz624jb3qoVHH/VOIqxQsaywMSrmH05nxW0h/MPF3TbOlz17 lbvmHmNCFIQ0Gz7dbxovxF52SW7alL0HAo+LmiVEFblSZ49RA1LzGyY4ZWCBu2CYNV 9QOvXghLB4PEweJ4AbtWcH7EOcbciNnYoSgTbjfQ= Date: Wed, 04 Jan 2023 17:46:51 -0800 To: mm-commits@vger.kernel.org, songmuchun@bytedance.com, peterx@redhat.com, mike.kravetz@oracle.com, axelrasmussen@google.com, jthoughton@google.com, akpm@linux-foundation.org From: Andrew Morton Subject: + hugetlb-unshare-some-pmds-when-splitting-vmas.patch added to mm-hotfixes-unstable branch Message-Id: <20230105014652.7C908C433F0@smtp.kernel.org> Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org The patch titled Subject: hugetlb: unshare some PMDs when splitting VMAs has been added to the -mm mm-hotfixes-unstable branch. Its filename is hugetlb-unshare-some-pmds-when-splitting-vmas.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/hugetlb-unshare-some-pmds-when-splitting-vmas.patch This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: James Houghton Subject: hugetlb: unshare some PMDs when splitting VMAs Date: Wed, 4 Jan 2023 23:19:10 +0000 PMD sharing can only be done in PUD_SIZE-aligned pieces of VMAs; however, it is possible that HugeTLB VMAs are split without unsharing the PMDs first. Without this fix, it is possible to hit the uffd-wp-related WARN_ON_ONCE in hugetlb_change_protection [1]. The key there is that hugetlb_unshare_all_pmds will not attempt to unshare PMDs in non-PUD_SIZE-aligned sections of the VMA. It might seem ideal to unshare in hugetlb_vm_op_open, but we need to unshare in both the new and old VMAs, so unsharing in hugetlb_vm_op_split seems natural. [1]: https://lore.kernel.org/linux-mm/CADrL8HVeOkj0QH5VZZbRzybNE8CG-tEGFshnA+bG9nMgcWtBSg@mail.gmail.com/ Link: https://lkml.kernel.org/r/20230104231910.1464197-1-jthoughton@google.com Fixes: 6dfeaff93be1 ("hugetlb/userfaultfd: unshare all pmds for hugetlbfs when register wp") Signed-off-by: James Houghton Cc: Axel Rasmussen Cc: Mike Kravetz Cc: Muchun Song Cc: Peter Xu Signed-off-by: Andrew Morton --- mm/hugetlb.c | 44 +++++++++++++++++++++++++++++++++++--------- 1 file changed, 35 insertions(+), 9 deletions(-) --- a/mm/hugetlb.c~hugetlb-unshare-some-pmds-when-splitting-vmas +++ a/mm/hugetlb.c @@ -94,6 +94,8 @@ static int hugetlb_acct_memory(struct hs static void hugetlb_vma_lock_free(struct vm_area_struct *vma); static void hugetlb_vma_lock_alloc(struct vm_area_struct *vma); static void __hugetlb_vma_unlock_write_free(struct vm_area_struct *vma); +static void hugetlb_unshare_pmds(struct vm_area_struct *vma, + unsigned long start, unsigned long end); static inline bool subpool_is_free(struct hugepage_subpool *spool) { @@ -4834,6 +4836,25 @@ static int hugetlb_vm_op_split(struct vm { if (addr & ~(huge_page_mask(hstate_vma(vma)))) return -EINVAL; + + /* + * PMD sharing is only possible for PUD_SIZE-aligned address ranges + * in HugeTLB VMAs. If we will lose PUD_SIZE alignment due to this + * split, unshare PMDs in the PUD_SIZE interval surrounding addr now. + */ + if (addr & ~PUD_MASK) { + /* + * hugetlb_vm_op_split is called right before we attempt to + * split the VMA. We will need to unshare PMDs in the old and + * new VMAs, so let's unshare before we split. + */ + unsigned long floor = addr & PUD_MASK; + unsigned long ceil = floor + PUD_SIZE; + + if (floor >= vma->vm_start && ceil <= vma->vm_end) + hugetlb_unshare_pmds(vma, floor, ceil); + } + return 0; } @@ -7322,26 +7343,21 @@ void move_hugetlb_state(struct folio *ol } } -/* - * This function will unconditionally remove all the shared pmd pgtable entries - * within the specific vma for a hugetlbfs memory range. - */ -void hugetlb_unshare_all_pmds(struct vm_area_struct *vma) +static void hugetlb_unshare_pmds(struct vm_area_struct *vma, + unsigned long start, + unsigned long end) { struct hstate *h = hstate_vma(vma); unsigned long sz = huge_page_size(h); struct mm_struct *mm = vma->vm_mm; struct mmu_notifier_range range; - unsigned long address, start, end; + unsigned long address; spinlock_t *ptl; pte_t *ptep; if (!(vma->vm_flags & VM_MAYSHARE)) return; - start = ALIGN(vma->vm_start, PUD_SIZE); - end = ALIGN_DOWN(vma->vm_end, PUD_SIZE); - if (start >= end) return; @@ -7373,6 +7389,16 @@ void hugetlb_unshare_all_pmds(struct vm_ mmu_notifier_invalidate_range_end(&range); } +/* + * This function will unconditionally remove all the shared pmd pgtable entries + * within the specific vma for a hugetlbfs memory range. + */ +void hugetlb_unshare_all_pmds(struct vm_area_struct *vma) +{ + hugetlb_unshare_pmds(vma, ALIGN(vma->vm_start, PUD_SIZE), + ALIGN_DOWN(vma->vm_end, PUD_SIZE)); +} + #ifdef CONFIG_CMA static bool cma_reserve_called __initdata; _ Patches currently in -mm which might be from jthoughton@google.com are hugetlb-unshare-some-pmds-when-splitting-vmas.patch