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 240FCC433EF for ; Mon, 4 Jul 2022 23:04:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230011AbiGDXEr (ORCPT ); Mon, 4 Jul 2022 19:04:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49870 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233719AbiGDXEd (ORCPT ); Mon, 4 Jul 2022 19:04:33 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C8FA1FD28 for ; Mon, 4 Jul 2022 16:04:31 -0700 (PDT) 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 5F1AA617A2 for ; Mon, 4 Jul 2022 23:04:31 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id AFAC5C3411E; Mon, 4 Jul 2022 23:04:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1656975870; bh=6ee7czDD1UA97+BiRdVjVtlnJ4+xkmFcGXXFKRfa81E=; h=Date:To:From:Subject:From; b=f3z96VZIjL7xnqeJqZC3SuGrgImdO1LmCPzgeZ3mefu7S+oLz3oYlsQsEz13/edS2 O0sRA9unh2BvjMVTT6G9FSCfmIiCdLavHxCCwWUMXZ1VBJ7gam43X15RCIyDG05n8n kv0xJEjgEQkrI4y8+bP+RM3QyQpA8Ni2bhVZw69M= Date: Mon, 04 Jul 2022 16:04:30 -0700 To: mm-commits@vger.kernel.org, zokeefe@google.com, willy@infradead.org, songmuchun@bytedance.com, shy828301@gmail.com, linmiaohe@huawei.com, akpm@linux-foundation.org From: Andrew Morton Subject: + mm-huge_memory-comment-the-subtly-logic-in-__split_huge_pmd.patch added to mm-unstable branch Message-Id: <20220704230430.AFAC5C3411E@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/huge_memory: comment the subtly logic in __split_huge_pmd has been added to the -mm mm-unstable branch. Its filename is mm-huge_memory-comment-the-subtly-logic-in-__split_huge_pmd.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-huge_memory-comment-the-subtly-logic-in-__split_huge_pmd.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: Miaohe Lin Subject: mm/huge_memory: comment the subtly logic in __split_huge_pmd Date: Mon, 4 Jul 2022 21:22:00 +0800 It's dangerous and wrong to call page_folio(pmd_page(*pmd)) when pmd isn't present. But the caller guarantees pmd is present when folio is set. So we should be safe here. Add comment to make it clear. Link: https://lkml.kernel.org/r/20220704132201.14611-16-linmiaohe@huawei.com Signed-off-by: Miaohe Lin Cc: Matthew Wilcox Cc: Muchun Song Cc: Yang Shi Cc: Zach O'Keefe Signed-off-by: Andrew Morton --- mm/huge_memory.c | 4 ++++ 1 file changed, 4 insertions(+) --- a/mm/huge_memory.c~mm-huge_memory-comment-the-subtly-logic-in-__split_huge_pmd +++ a/mm/huge_memory.c @@ -2335,6 +2335,10 @@ void __split_huge_pmd(struct vm_area_str if (pmd_trans_huge(*pmd) || pmd_devmap(*pmd) || is_pmd_migration_entry(*pmd)) { + /* + * It's safe to call pmd_page when folio is set because it's + * guaranteed that pmd is present. + */ if (folio && folio != page_folio(pmd_page(*pmd))) goto out; __split_huge_pmd_locked(vma, pmd, range.start, freeze); _ Patches currently in -mm which might be from linmiaohe@huawei.com are mm-page_alloc-minor-clean-up-for-memmap_init_compound.patch mm-mmapc-fix-missing-call-to-vm_unacct_memory-in-mmap_region.patch filemap-minor-cleanup-for-filemap_write_and_wait_range.patch mm-huge_memory-use-flush_pmd_tlb_range-in-move_huge_pmd.patch mm-huge_memory-access-vm_page_prot-with-read_once-in-remove_migration_pmd.patch mm-huge_memory-fix-comment-of-__pud_trans_huge_lock.patch mm-huge_memory-use-helper-touch_pud-in-huge_pud_set_accessed.patch mm-huge_memory-use-helper-touch_pmd-in-huge_pmd_set_accessed.patch mm-huge_memory-rename-mmun_start-to-haddr-in-remove_migration_pmd.patch mm-huge_memory-use-helper-function-vma_lookup-in-split_huge_pages_pid.patch mm-huge_memory-use-helper-macro-__attr_rw.patch mm-huge_memory-fix-comment-in-zap_huge_pud.patch mm-huge_memory-check-pmd_present-first-in-is_huge_zero_pmd.patch mm-huge_memory-try-to-free-subpage-in-swapcache-when-possible.patch mm-huge_memory-minor-cleanup-for-split_huge_pages_all.patch mm-huge_memory-fix-comment-of-page_deferred_list.patch mm-huge_memory-correct-comment-of-prep_transhuge_page.patch mm-huge_memory-comment-the-subtly-logic-in-__split_huge_pmd.patch mm-huge_memory-use-helper-macro-is_err_or_null-in-split_huge_pages_pid.patch