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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id ADD83F8E4B3 for ; Fri, 17 Apr 2026 07:21:43 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id BC1C96B00A4; Fri, 17 Apr 2026 03:21:42 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id B71E06B00A5; Fri, 17 Apr 2026 03:21:42 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A87C86B00A6; Fri, 17 Apr 2026 03:21:42 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 9682C6B00A4 for ; Fri, 17 Apr 2026 03:21:42 -0400 (EDT) Received: from smtpin23.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id BD96BC3660 for ; Fri, 17 Apr 2026 07:21:41 +0000 (UTC) X-FDA: 84667202802.23.DD2F3FB Received: from out30-119.freemail.mail.aliyun.com (out30-119.freemail.mail.aliyun.com [115.124.30.119]) by imf30.hostedemail.com (Postfix) with ESMTP id BC8FF80007 for ; Fri, 17 Apr 2026 07:21:38 +0000 (UTC) Authentication-Results: imf30.hostedemail.com; dkim=pass header.d=linux.alibaba.com header.s=default header.b=gZpCuBNf; spf=pass (imf30.hostedemail.com: domain of ying.huang@linux.alibaba.com designates 115.124.30.119 as permitted sender) smtp.mailfrom=ying.huang@linux.alibaba.com; dmarc=pass (policy=none) header.from=linux.alibaba.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1776410500; a=rsa-sha256; cv=none; b=Zzdy+k/umUxqhgGd43FRXnU+BiIP8MV0StjHK5DqrnXuB/Ylx8O74LT1ZQZa352lw+5sBf PR8G4DyiIH8j4mb2l5Z9+/KwAOQkSBrRE6jSA2o6fYNYPFLmXCMKxmyOUdmikUaqrYGYmW oCyk/6fkvGFwi6lOsU75eoy6pgokRVY= ARC-Authentication-Results: i=1; imf30.hostedemail.com; dkim=pass header.d=linux.alibaba.com header.s=default header.b=gZpCuBNf; spf=pass (imf30.hostedemail.com: domain of ying.huang@linux.alibaba.com designates 115.124.30.119 as permitted sender) smtp.mailfrom=ying.huang@linux.alibaba.com; dmarc=pass (policy=none) header.from=linux.alibaba.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1776410500; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=93oxKOORlnBXcsnliXcH+HsS5Rt3NUtTsFQEOXV4lUw=; b=bNUQYKq6kg2Nw4A1iQD3PxevSMrVM+bA3XzWbv4Scd3ubediQzWjYHLkaMVD9nOqtRRbz0 mJ28RlSk9ZgM8ODobw/XE+U5A43i8ePrj69YzoJKrHhha5nFal/kjk6PRNWM8cDZ8EcWrI CrW5hnP3kG23OolFzzkDzApbOd6NYgg= DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1776410494; h=From:To:Subject:Date:Message-ID:MIME-Version:Content-Type; bh=93oxKOORlnBXcsnliXcH+HsS5Rt3NUtTsFQEOXV4lUw=; b=gZpCuBNf1cnhjIyGxD0NUfHO9DP7y3nZHXg1cVqNVHA8rj8rpQj7RgfrHCtHhPURft8ioT3FO/2AsQFaUI1Y6wtqkWvmph5aqqr66evEZrzT9FaWUMbXsu/R9K4mDgfho9a9TbI3jSvbNQz83Jg5oAvTX59IyzNh9xlZEVRUdGo= X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R171e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=maildocker-contentspam033037009110;MF=ying.huang@linux.alibaba.com;NM=1;PH=DS;RN=12;SR=0;TI=SMTPD_---0X1AZ8vF_1776410492; Received: from DESKTOP-5N7EMDA(mailfrom:ying.huang@linux.alibaba.com fp:SMTPD_---0X1AZ8vF_1776410492 cluster:ay36) by smtp.aliyun-inc.com; Fri, 17 Apr 2026 15:21:33 +0800 From: "Huang, Ying" To: "David Hildenbrand (Arm)" Cc: Sunny Patel , Andrew Morton , Zi Yan , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Gregory Price , Alistair Popple , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm/migrate_device: Cleanup up PMD Checks and warnings In-Reply-To: (David Hildenbrand's message of "Thu, 16 Apr 2026 21:44:15 +0200") References: <20260414141344.29949-1-nueralspacetech@gmail.com> Date: Fri, 17 Apr 2026 15:21:31 +0800 Message-ID: <87y0imhx1g.fsf@DESKTOP-5N7EMDA> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain; charset=ascii X-Rspamd-Queue-Id: BC8FF80007 X-Stat-Signature: er8ub5gpxez3f5j87yhq4fncbsc3n11t X-Rspam-User: X-Rspamd-Server: rspam09 X-HE-Tag: 1776410498-672956 X-HE-Meta: U2FsdGVkX1/FDHDoShc3thefMu5U60aHzi1zGUL2JzB6puUv6YEQZ9nlCMg/DSVLxykEZyocxAxCj8GmkMyh+Mpf5O1TACiSE3Aq5Y4O4H1u4Aju+bl9U4IDjjVaDgBO6E90yb13/OMKR/o19hIeCYxQEo3KjfiTvtjSs6ifEglpQawL55jIYl4PKCHan/zmcgD7snUEpMGigbb70pUYToA3k69iBaptF6uwZWiEz5DdCWTIbtL86hgK2aoJ8Dy6eF2c80No5Wu30IGBK4CB5zOQagY9gxLk1Epv/uKWVF1KwcitF8bGm+5b1QCWGwUoSIDi4uMpfsE2eWLW6U7RTsN5mYViiPomkZMwD7GbMGLg+TtRO+LyOPIsOCRde9kpBuikBGtcFeSd8Jc/MzMQ3UTztAnPKsue6/J+vGHoeXfPBqMF3NZeeNDCkv33cIkv4IHNiMwCEVW7yy9TSzpHfrb9mJuJJr+XrmjvSbE8VtzrMFzLE5Z+37/BYMWbv6viU/K2yqgjFX3VrRpQZs4pfIRGSoOYpfkfT6xOQjkZisj0bRU+n8Y4o4Oa++4YSWey3IEM8AXcC0kzDdYafjHNd+ee3JHsF02n2w15mgMsD3LP3MxkNRFLRcef9pyLG+rhf6zvNhgGgTjZnHAWxSTJHCLzGwplCxjYiW3H47PJ3932btkPu4HpC6PhX2CHKgAYbCapJR+ims/c8042YqhzLah/25lMJE9saL5GyGE0uR//c67AfLbc9t5MpGnQseDeKkU7D0/dWTm4nEBMjrKYc7/a7iJ/r+2N+D8Q3YwirAyzi5qQKXGEhmC0XO/r3mXye4gRP8PwBLxJVyyoTZj3yw2xCkR/Fc3fU4s1oOlSGcM3jzr4AvHMv7QoxPgQifZpLg9KU9DQTZTCPddinowUzF2shdPH2N/UsQ2kuexz0oN4708AGGTyVS8gbSCTHBv2XAi+PylT+3PCaEjFnVI xWIE6+ZA lqoTMQuz+i7Z+RTUm/oHVXVxiEhmIT1ulFU7z8MKHu4EbmQ2iMknYsrZn/lzL93aYK2M8KeuQJrfnyUUkdUlnEVkDHfaXSg4jpFbKFVevDa914P81/pLBIGi3JYSgEx51bHCdPlRza+44z6gMJjn0KrT1Yd9ydYqpkzWYfRPaRcJrPCMfKxzZvxDF972G5Jgq2zxOiY/AsZnwMZEUeDy7EahY30cJAcsg6ogtsq0McNbQWuAbYO1gYhlmodtqnDWTFJK0tdpCt2Voidn3fcElmW73UxeeNp9flHP4P8VT+zqb1nwjMcWrmSMsNkXprUwOhxxQbL5/+gzgDL4gsWO8VkCN9+BqjjdFiktxmhj8Ry6kB7bQBFwy/Va/PSrSNeUjAj1OfHhJCCFFuwryBMK8jvYa+Fp87x2VbANFRGzinB/dHhcifEGIHn2vFg== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: "David Hildenbrand (Arm)" writes: > On 4/14/26 16:13, Sunny Patel wrote: >> Remove the odd VM_WARN_ON_FOLIO(!folio, folio) usage and replace it >> with a simpler VM_WARN_ON_ONCE(!folio) check. >> >> Drop the redundant VM_WARN_ON_ONCE(!pmd_none(*pmdp) && >> !is_huge_zero_pmd(*pmdp)). >> >> Refactor the PMD checks to use pmd_present(), making the control flow >> clearer and avoiding duplicate condition checks. >> >> Signed-off-by: Sunny Patel >> --- >> mm/migrate_device.c | 8 ++++---- >> 1 file changed, 4 insertions(+), 4 deletions(-) >> >> diff --git a/mm/migrate_device.c b/mm/migrate_device.c >> index 8079676c8f1f..fe1c1999aa2d 100644 >> --- a/mm/migrate_device.c >> +++ b/mm/migrate_device.c >> @@ -807,8 +807,7 @@ static int migrate_vma_insert_huge_pmd_page(struct migrate_vma *migrate, >> bool flush = false; >> unsigned long i; >> >> - VM_WARN_ON_FOLIO(!folio, folio); >> - VM_WARN_ON_ONCE(!pmd_none(*pmdp) && !is_huge_zero_pmd(*pmdp)); >> + VM_WARN_ON_ONCE(!folio); > > I'd test for "page" here instead. But it doesn't matter as of today. > >> >> if (!thp_vma_suitable_order(vma, addr, HPAGE_PMD_ORDER)) >> return -EINVAL; >> @@ -865,12 +864,13 @@ static int migrate_vma_insert_huge_pmd_page(struct migrate_vma *migrate, >> if (userfaultfd_missing(vma)) >> goto unlock_abort; >> >> - if (!pmd_none(*pmdp)) { >> + if (pmd_present(*pmdp)) { >> if (!is_huge_zero_pmd(*pmdp)) >> goto unlock_abort; >> flush = true; >> - } else if (!pmd_none(*pmdp)) >> + } else if (!pmd_none(*pmdp)) { >> goto unlock_abort; >> + } >> >> add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR); >> folio_add_new_anon_rmap(folio, vma, addr, RMAP_EXCLUSIVE); > > is_huge_zero_pmd() checks pmd_present(), so we didn't have a bug before. > > We could also do: > > if (is_huge_zero_pmd(*pmdp)) { > flush = true; > } else if (!pmd_none(*pmdp)) { > goto unlock_abort; > } I think that this is better. And because the patch is for code cleanup, why not do it better. > But I don't particularly care > > Acked-by: David Hildenbrand (Arm) --- Best Regards, Huang, Ying