From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta1.migadu.com (out-157.mta1.migadu.com [95.215.58.157]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 99A744964F for ; Sat, 15 Aug 2026 03:54:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.157 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786766090; cv=none; b=LQX4LogdI4upX7YQREfIdmO57fPAAVOtS3QCR5xGOnsRVag7OXINhMCTrFfcTFB0O7hkUTFpCYP1zQe86j6TrOyF/qytT4DejG4ZsWT6YkmfGAqswUOve58PQV5mT+VyCeacx7x/f1Hc0DJzJqtJPunYfl8OeG2EQ3Q/lmeO4E8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786766090; c=relaxed/simple; bh=8l7ix46u22DBJHyDAdgQxSxR4YiD9zuO4qj39ojr/7w=; h=Content-Type:Mime-Version:Subject:From:In-Reply-To:Date:Cc: Message-Id:References:To; b=D8WidQIKf4ZzIZgLq8eNVmaDJwPNHs6+Av9+KFVyYnDx7j99Nj0KKLskjAWPwFPRbTcnTVhLfPGmAvnJZ1MFRGhhPzICqgRIyRRQ3gYCLFBJLhS3VS1tZjKQu4OAygDIFcky5Nau4R6JYrcErfmtug5EsOsRdOBRMz1jfa35YSU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=n6vNuCnq; arc=none smtp.client-ip=95.215.58.157 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="n6vNuCnq" X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=8l7ix46u22DBJHyDAdgQxSxR4YiD9zuO4qj39ojr/7w=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1786766083; v=1; x=1787370883; b=n6vNuCnqlI+pUIgmT+1QhowfklOkFkZVaBsLd0sqdwQ73kTDDww8x9/IGcVEghlUSSfL4KNP CXPuhZucti2Llk3SjptI3lYKb/84QB2F9sEuTtD06+KgD8Kxu5rI4rCumuY4lXEYdoZ/Cs5i3QF 3OCP5YVG8aYRdGJTF1BQciwI= X-Envelope-To: linux-kernel@vger.kernel.org Received: from smtpclient.apple (2409:8a00:1832:cf0:a88a:e36b:332d:205d) by mta12.migadu.com with ESMTPS id 0ecf74c5aca00b18; Sat, 15 Aug 2026 03:54:43 +0000 X-Migadu-Flow: FLOW_OUT Content-Type: text/plain; charset=us-ascii Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3864.600.51.1.1\)) Subject: Re: [PATCH 1/1] mm/hugetlb: keep max_huge_pages when dissolving surplus folios From: Muchun Song In-Reply-To: <20260814083027.1419487-1-xialonglong2025@163.com> Date: Sat, 15 Aug 2026 11:54:29 +0800 Cc: Oscar Salvador , David Hildenbrand , Andrew Morton , Jinjiang Tu , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Longlong Xia Content-Transfer-Encoding: quoted-printable Message-Id: References: <20260814083027.1419487-1-xialonglong2025@163.com> To: Longlong Xia X-Mailer: Apple Mail (2.3864.600.51.1.1) > On Aug 14, 2026, at 16:30, Longlong Xia = wrote: >=20 > From: Longlong Xia >=20 > dissolve_free_hugetlb_folio() can remove a free folio as surplus when > its node has surplus pages. In that case remove_hugetlb_folio() > decrements both nr_huge_pages and surplus_huge_pages, leaving the > persistent pool size unchanged. >=20 > Updating max_huge_pages as if a persistent folio had been removed can > therefore corrupt the persistent pool target and underflow it when > max_huge_pages is zero. Keep max_huge_pages unchanged for surplus > folios, including the vmemmap restoration rollback path. >=20 > Fixes: cb402bbdabca ("mm/hugetlb: fix surplus pages in = dissolve_free_huge_page()") > Assisted-by: Codex:gpt-5.6-sol > Signed-off-by: Longlong Xia Reviewed-by: Muchun Song Thanks.