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 BA1E0FA3747 for ; Fri, 28 Oct 2022 21:08:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229919AbiJ1VHi (ORCPT ); Fri, 28 Oct 2022 17:07:38 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52940 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229887AbiJ1VHU (ORCPT ); Fri, 28 Oct 2022 17:07:20 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D7B0424A54F; Fri, 28 Oct 2022 14:07:18 -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 ams.source.kernel.org (Postfix) with ESMTPS id 8C402B82CC0; Fri, 28 Oct 2022 21:07:17 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 152BCC433C1; Fri, 28 Oct 2022 21:07:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1666991236; bh=sY70FcN0eCqMVQT80tlvLTJqH7xW9uNa7mImbILhJhU=; h=Date:To:From:Subject:From; b=R2dmzl+jfED8NCFYFJ5bm00rUAFEmNWuZvs8h1tAljn/S69lYT0wJ12+puo7Nlpw1 O771+SxoDW/N5Q4mdPHzKSCypn5iLFADpoZI1PHHtnCfWbunykEIRPvVOdLWm430ql 3FzZYOh83FqUrHvhDIecPTEkSlwpGmz+MXB6XYZE= Date: Fri, 28 Oct 2022 14:07:15 -0700 To: mm-commits@vger.kernel.org, willy@infradead.org, stable@vger.kernel.org, mgorman@techsingularity.net, hughd@google.com, akpm@linux-foundation.org From: Andrew Morton Subject: [merged mm-hotfixes-stable] mm-prep_compound_tail-clear-page-private.patch removed from -mm tree Message-Id: <20221028210716.152BCC433C1@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: prep_compound_tail() clear page->private has been removed from the -mm tree. Its filename was mm-prep_compound_tail-clear-page-private.patch This patch was dropped because it was merged into the mm-hotfixes-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm ------------------------------------------------------ From: Hugh Dickins Subject: mm: prep_compound_tail() clear page->private Date: Sat, 22 Oct 2022 00:51:06 -0700 (PDT) Although page allocation always clears page->private in the first page or head page of an allocation, it has never made a point of clearing page->private in the tails (though 0 is often what is already there). But now commit 71e2d666ef85 ("mm/huge_memory: do not clobber swp_entry_t during THP split") issues a warning when page_tail->private is found to be non-0 (unless it's swapcache). Change that warning to dump page_tail (which also dumps head), instead of just the head: so far we have seen dead000000000122, dead000000000003, dead000000000001 or 0000000000000002 in the raw output for tail private. We could just delete the warning, but today's consensus appears to want page->private to be 0, unless there's a good reason for it to be set: so now clear it in prep_compound_tail() (more general than just for THP; but not for high order allocation, which makes no pass down the tails). Link: https://lkml.kernel.org/r/1c4233bb-4e4d-5969-fbd4-96604268a285@google.com Fixes: 71e2d666ef85 ("mm/huge_memory: do not clobber swp_entry_t during THP split") Signed-off-by: Hugh Dickins Acked-by: Mel Gorman Cc: Matthew Wilcox (Oracle) Cc: Signed-off-by: Andrew Morton --- --- a/mm/huge_memory.c~mm-prep_compound_tail-clear-page-private +++ a/mm/huge_memory.c @@ -2462,7 +2462,7 @@ static void __split_huge_page_tail(struc * Fix up and warn once if private is unexpectedly set. */ if (!folio_test_swapcache(page_folio(head))) { - VM_WARN_ON_ONCE_PAGE(page_tail->private != 0, head); + VM_WARN_ON_ONCE_PAGE(page_tail->private != 0, page_tail); page_tail->private = 0; } --- a/mm/page_alloc.c~mm-prep_compound_tail-clear-page-private +++ a/mm/page_alloc.c @@ -807,6 +807,7 @@ static void prep_compound_tail(struct pa p->mapping = TAIL_MAPPING; set_compound_head(p, head); + set_page_private(p, 0); } void prep_compound_page(struct page *page, unsigned int order) _ Patches currently in -mm which might be from hughd@google.com are