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 1DD31C001B2 for ; Fri, 16 Dec 2022 17:18:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231747AbiLPRSN (ORCPT ); Fri, 16 Dec 2022 12:18:13 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37796 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231736AbiLPRSA (ORCPT ); Fri, 16 Dec 2022 12:18:00 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CC1892A275 for ; Fri, 16 Dec 2022 09:17:58 -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 660C561FD7 for ; Fri, 16 Dec 2022 17:17:58 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B7970C433D2; Fri, 16 Dec 2022 17:17:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1671211077; bh=qIKh66+1pSJVc4RNlaHXkcivA3MbziA5Sl76gqkfqus=; h=Date:To:From:Subject:From; b=rA15DIoIdj/+TV0AE75osnK4E7GeFUXV3F9pzKm7IpWcFIX3psNOzEHscG18eqt1e HcU5zsTFkBVgfS8/6HtCEn97MosSiKCKzuiUSkVoBEVJ8FQcy6K+QSfL7On3H5Ch5I JkEAIObckR+KrBKq3cHKYifrxDvf+f0L24E1cGjg= Date: Fri, 16 Dec 2022 09:17:56 -0800 To: mm-commits@vger.kernel.org, songmuchun@bytedance.com, riel@surriel.com, nadav.amit@gmail.com, mike.kravetz@oracle.com, linmiaohe@huawei.com, jthoughton@google.com, jhubbard@nvidia.com, jannh@google.com, david@redhat.com, aarcange@redhat.com, peterx@redhat.com, akpm@linux-foundation.org From: Andrew Morton Subject: + mm-hugetlb-make-userfaultfd_huge_must_wait-safe-to-pmd-unshare.patch added to mm-unstable branch Message-Id: <20221216171757.B7970C433D2@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: mm/hugetlb: make userfaultfd_huge_must_wait() safe to pmd unshare has been added to the -mm mm-unstable branch. Its filename is mm-hugetlb-make-userfaultfd_huge_must_wait-safe-to-pmd-unshare.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-hugetlb-make-userfaultfd_huge_must_wait-safe-to-pmd-unshare.patch This patch will later appear in the mm-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: Peter Xu Subject: mm/hugetlb: make userfaultfd_huge_must_wait() safe to pmd unshare Date: Fri, 16 Dec 2022 10:52:17 -0500 We can take the hugetlb walker lock, here taking vma lock directly. Link: https://lkml.kernel.org/r/20221216155217.2043700-1-peterx@redhat.com Signed-off-by: Peter Xu Reviewed-by: David Hildenbrand Reviewed-by: Mike Kravetz Reviewed-by: John Hubbard Cc: Andrea Arcangeli Cc: James Houghton Cc: Jann Horn Cc: Miaohe Lin Cc: Muchun Song Cc: Nadav Amit Cc: Rik van Riel Signed-off-by: Andrew Morton --- fs/userfaultfd.c | 20 ++++++++++++++++---- 1 file changed, 16 insertions(+), 4 deletions(-) --- a/fs/userfaultfd.c~mm-hugetlb-make-userfaultfd_huge_must_wait-safe-to-pmd-unshare +++ a/fs/userfaultfd.c @@ -376,7 +376,8 @@ static inline unsigned int userfaultfd_g */ vm_fault_t handle_userfault(struct vm_fault *vmf, unsigned long reason) { - struct mm_struct *mm = vmf->vma->vm_mm; + struct vm_area_struct *vma = vmf->vma; + struct mm_struct *mm = vma->vm_mm; struct userfaultfd_ctx *ctx; struct userfaultfd_wait_queue uwq; vm_fault_t ret = VM_FAULT_SIGBUS; @@ -403,7 +404,7 @@ vm_fault_t handle_userfault(struct vm_fa */ mmap_assert_locked(mm); - ctx = vmf->vma->vm_userfaultfd_ctx.ctx; + ctx = vma->vm_userfaultfd_ctx.ctx; if (!ctx) goto out; @@ -493,6 +494,15 @@ vm_fault_t handle_userfault(struct vm_fa blocking_state = userfaultfd_get_blocking_state(vmf->flags); + /* + * Take the vma lock now, in order to safely call + * userfaultfd_huge_must_wait() later. Since acquiring the + * (sleepable) vma lock can modify the current task state, that + * must be before explicitly calling set_current_state(). + */ + if (is_vm_hugetlb_page(vma)) + hugetlb_vma_lock_read(vma); + spin_lock_irq(&ctx->fault_pending_wqh.lock); /* * After the __add_wait_queue the uwq is visible to userland @@ -507,13 +517,15 @@ vm_fault_t handle_userfault(struct vm_fa set_current_state(blocking_state); spin_unlock_irq(&ctx->fault_pending_wqh.lock); - if (!is_vm_hugetlb_page(vmf->vma)) + if (!is_vm_hugetlb_page(vma)) must_wait = userfaultfd_must_wait(ctx, vmf->address, vmf->flags, reason); else - must_wait = userfaultfd_huge_must_wait(ctx, vmf->vma, + must_wait = userfaultfd_huge_must_wait(ctx, vma, vmf->address, vmf->flags, reason); + if (is_vm_hugetlb_page(vma)) + hugetlb_vma_unlock_read(vma); mmap_read_unlock(mm); if (likely(must_wait && !READ_ONCE(ctx->released))) { _ Patches currently in -mm which might be from peterx@redhat.com are mm-uffd-fix-pte-marker-when-fork-without-fork-event.patch mm-fix-a-few-rare-cases-of-using-swapin-error-pte-marker.patch mm-uffd-always-wr-protect-pte-in-ptepmd_mkuffd_wp.patch mm-hugetlb-let-vma_offset_start-to-return-start.patch mm-hugetlb-dont-wait-for-migration-entry-during-follow-page.patch mm-hugetlb-document-huge_pte_offset-usage.patch mm-hugetlb-move-swap-entry-handling-into-vma-lock-when-faulted.patch mm-hugetlb-make-userfaultfd_huge_must_wait-safe-to-pmd-unshare.patch mm-hugetlb-make-hugetlb_follow_page_mask-safe-to-pmd-unshare.patch mm-hugetlb-make-follow_hugetlb_page-safe-to-pmd-unshare.patch mm-hugetlb-make-walk_hugetlb_range-safe-to-pmd-unshare.patch mm-hugetlb-introduce-hugetlb_walk.patch