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 5E366F01826 for ; Fri, 6 Mar 2026 10:47:50 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 85E966B0005; Fri, 6 Mar 2026 05:47:49 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 80C736B008A; Fri, 6 Mar 2026 05:47:49 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 718206B008C; Fri, 6 Mar 2026 05:47:49 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id 5CAA26B0005 for ; Fri, 6 Mar 2026 05:47:49 -0500 (EST) Received: from smtpin12.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 1CE2EC1F6B for ; Fri, 6 Mar 2026 10:47:49 +0000 (UTC) X-FDA: 84515312658.12.4C6C32D Received: from out-178.mta1.migadu.com (out-178.mta1.migadu.com [95.215.58.178]) by imf27.hostedemail.com (Postfix) with ESMTP id 41E8840006 for ; Fri, 6 Mar 2026 10:47:47 +0000 (UTC) Authentication-Results: imf27.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=NOfHMeXp; spf=pass (imf27.hostedemail.com: domain of usama.arif@linux.dev designates 95.215.58.178 as permitted sender) smtp.mailfrom=usama.arif@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1772794067; 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:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=tjPP1MkY7cVIKE6dM0lngCXvsWMfl9x5zuCWaBUpV24=; b=1Ly0asPILvEJ3Icwfm3uHS4iBG/nZodaoozhqLMzOhFOyIyyvIdoF+dXoz7A+swg8b71Wp 1UinTNgfd446zlV4jfZTSxTzCkcbs+J2GRD88vPj+MOyB4tVjjGgPqw9tNks1niBCWJmb0 UHRyk2EiEoaLW2y7MmyoB+tb2UEosGE= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1772794067; a=rsa-sha256; cv=none; b=2BC2Vq1rlvZWYGxFch0928NnT45R2CPBpb5tb0uoTeSd35ULql0U1rC2r2mFTal/dpt49b x26W5k1rRjhr9Xs9Idqb5ZhuTNj/YfqlKnNr3yuLp/KyULwzloLhpCYonGCD8FAtL8HbPR lzvSnw+0/0UIzOi0uJELV8JqGGNkB4c= ARC-Authentication-Results: i=1; imf27.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=NOfHMeXp; spf=pass (imf27.hostedemail.com: domain of usama.arif@linux.dev designates 95.215.58.178 as permitted sender) smtp.mailfrom=usama.arif@linux.dev; dmarc=pass (policy=none) header.from=linux.dev Message-ID: <3dd4399f-a138-4ec0-b3a8-0ce200423ebe@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1772794065; h=from:from: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:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=tjPP1MkY7cVIKE6dM0lngCXvsWMfl9x5zuCWaBUpV24=; b=NOfHMeXpi6Cr3mGYireNzPc4UXDrWxm689oejv2P7DpZe+niwQ5cKFZE8SCUo/wX3HR8w5 tZ/95TAThil5pEgo2sRPydEcoEMBDApYOgLMl1L44qQnR4nMQ3QDhEcdqIoKnQRa2iskft E9KTe9lhlr6eUH37SMjT6k5fL1LIIFk= Date: Fri, 6 Mar 2026 13:47:35 +0300 MIME-Version: 1.0 Subject: Re: [PATCH] mm/migrate_device: fix folio refcount leak on folio_split_unmapped failure Content-Language: en-GB To: Zi Yan Cc: =?UTF-8?Q?Mika_Penttil=C3=A4?= , Balbir Singh , Kiryl Shutsemau , matthew.brost@intel.com, npache@redhat.com, david@kernel.org, Usama Arif , Andrew Morton , linux-mm@kvack.org, joshua.hahnjy@gmail.com, hannes@cmpxchg.org, rakie.kim@sk.com, byungchul@sk.com, gourry@gourry.net, ying.huang@linux.alibaba.com, apopple@nvidia.com, riel@surriel.com, shakeel.butt@linux.dev, linux-kernel@vger.kernel.org, kernel-team@meta.com References: <20260304120132.3973445-1-usamaarif642@gmail.com> <5e59c077-9f06-4e45-86e1-ca696e6105b4@nvidia.com> <622eb392-8c04-473d-b42a-ecdc489799c4@linux.dev> <942f2df4-6fb5-415f-b7d4-87a83315890b@redhat.com> <80683d6d-ea38-4326-af5e-e4c173bb1930@redhat.com> <332c9e16-46c3-4e1c-898e-2cb0a87ba1fc@linux.dev> <7996d5c5-24db-4ef2-b88a-1b9d33f9e976@linux.dev> <1EAE2E58-7A71-4B59-B1EF-3A3C753DDC1E@nvidia.com> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Usama Arif In-Reply-To: <1EAE2E58-7A71-4B59-B1EF-3A3C753DDC1E@nvidia.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT X-Stat-Signature: uui8y5x6n43efux7agzecrbakzxk8c1d X-Rspam-User: X-Rspamd-Queue-Id: 41E8840006 X-Rspamd-Server: rspam12 X-HE-Tag: 1772794067-344019 X-HE-Meta: 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 DLTUDGir 5Qy69iwslrCxhCNeE16G6HZ5gc79tiNT8fP1TkqrIPXBk4fZ5n7EqEGM5C8+XLPDNgGLNIGVMysg/u/rHkkhl4CYKg/9QRjR2gAMAJwaA4NFRbaLAcVD2mqy3MqtyYAO2RoT+MM72hhxnsisRuLPkNIh0pg9U2vIMNintokJi3zhcsKa6NHdqtUZ/dYSM50cf3t0ZhMhp3L7VzaPmOYYuJiZnj37wEh9qfxPOwZZt+y/1IPODFU+o1TI9KO2mhs7fdx0dMVfxZ3xVI9PLx0FgFBRMgQA1jmxqozCs5qKlcubXTwMAVoUcbuzkdoZNTj7gwyuymRKJSuzFsh5dW7u6xQIs6bSGkyYCq/8OPpJRih7sOIPFqBGxddgZgA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: > > I do not think there is a need to explain why there is no folio_put() > below. How about below? > > 1. it makes sure the folio has the right ref count, > 2. it explains folio_get() is for split_huge_pmd_address() instead of > folio_split_unmapped(). > > diff --git a/mm/migrate_device.c b/mm/migrate_device.c > index 0a8b31939640f..0b31b878210ba 100644 > --- a/mm/migrate_device.c > +++ b/mm/migrate_device.c > @@ -914,8 +914,14 @@ static int migrate_vma_split_unmapped_folio(struct migrate_vma *migrate, > unsigned long flags; > int ret = 0; > > + VM_WARN_ON_ONCE(folio_ref_count(folio) == 1); Thanks! I have sent it in [1]. One thing is, I think you mean over here folio_ref_count(folio) != 1, right? Thats what the patch has. [1] https://lore.kernel.org/all/20260306104409.3915811-1-usama.arif@linux.dev/ > + /* > + * take a reference, since split_huge_pmd_address() with freeze = true > + * drops a reference at the end. > + */ > folio_get(folio); > split_huge_pmd_address(migrate->vma, addr, true); > + > ret = folio_split_unmapped(folio, 0); > if (ret) > return ret; > > >> >>>> >>>> >>>> [1] https://gist.github.com/uarif1/65e1e816af7aa0ae38dd6ec64d62a993 >>>> [2] https://gist.github.com/uarif1/79ea9500667daa4e2ef09cb5d308f041 >>>> [3] https://gist.github.com/uarif1/8a35a6c65ba8b3a1c1dfe72dc30e821d >>> >>> >>> Best Regards, >>> Yan, Zi > > > Best Regards, > Yan, Zi