From nobody Wed Dec 17 10:21:24 2025 Received: from szxga04-in.huawei.com (szxga04-in.huawei.com [45.249.212.190]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 33061148318 for ; Thu, 11 Jul 2024 07:28:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.190 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720682899; cv=none; b=Z6vtQZgvnsiw9GfZQVwIs/ZNH9P8x1jr8shPjaETJ21WupzgksiSgTrhAcWXTg1KdmUyMFjeGap897KuAengHdw0I4kSDg9HgXDXRSvZfedOyW7fyT3qsAYbFZhJWTjd3ZarPzYzp4sMQxD1yGmc/LiDGBekuAwWkZ0HoDW6LDI= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720682899; c=relaxed/simple; bh=LooyK1nesgxXPrZ4cwneopS5lVW518hX1UEmAKtwnlU=; h=From:To:CC:Subject:Date:Message-ID:MIME-Version:Content-Type; b=WWubUbaJZ9LC9pHl3/f97GP0mDgt/M2TXGi2PIPmoVNHrFqGahuqVL8qsPfQKtG2Z0Qabcogpq3YrbCDNZeoFT1CcNUYhYt+jSF3e8XSiW7GUhHJl96s+PxxhOqbxYDrZqt5lrBq7G1GZnzpS5TpD216yIbsyeDmYVzRsENtIBo= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; arc=none smtp.client-ip=45.249.212.190 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.19.88.163]) by szxga04-in.huawei.com (SkyGuard) with ESMTP id 4WKR6n1FQrz2Cl8D; Thu, 11 Jul 2024 15:24:01 +0800 (CST) Received: from kwepemi100008.china.huawei.com (unknown [7.221.188.57]) by mail.maildlp.com (Postfix) with ESMTPS id 5C297180018; Thu, 11 Jul 2024 15:28:14 +0800 (CST) Received: from huawei.com (10.90.53.73) by kwepemi100008.china.huawei.com (7.221.188.57) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.1.2507.39; Thu, 11 Jul 2024 15:28:13 +0800 From: Jinjie Ruan To: , , , , , CC: Subject: [PATCH v2 RESEND] crash: Fix x86_32 memory reserve dead loop retry bug Date: Thu, 11 Jul 2024 15:32:31 +0800 Message-ID: <20240711073231.1289883-1-ruanjinjie@huawei.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) To kwepemi100008.china.huawei.com (7.221.188.57) Content-Type: text/plain; charset="utf-8" On x86_32 Qemu machine with 1GB memory, the cmdline "crashkernel=3D1G,high" will cause system stall as below: ACPI: Reserving FACP table memory at [mem 0x3ffe18b8-0x3ffe192b] ACPI: Reserving DSDT table memory at [mem 0x3ffe0040-0x3ffe18b7] ACPI: Reserving FACS table memory at [mem 0x3ffe0000-0x3ffe003f] ACPI: Reserving APIC table memory at [mem 0x3ffe192c-0x3ffe19bb] ACPI: Reserving HPET table memory at [mem 0x3ffe19bc-0x3ffe19f3] ACPI: Reserving WAET table memory at [mem 0x3ffe19f4-0x3ffe1a1b] 143MB HIGHMEM available. 879MB LOWMEM available. mapped low ram: 0 - 36ffe000 low ram: 0 - 36ffe000 (stall here) The reason is that the CRASH_ADDR_LOW_MAX is equal to CRASH_ADDR_HIGH_MAX on x86_32, the first high crash kernel memory reservation will fail, then go into the "retry" loop and never came out as below. -> reserve_crashkernel_generic() and high is true -> alloc at [CRASH_ADDR_LOW_MAX, CRASH_ADDR_HIGH_MAX] fail -> alloc at [0, CRASH_ADDR_LOW_MAX] fail and repeatedly (because CRASH_ADDR_LOW_MAX =3D CRASH_ADDR_HIGH_MAX). Fix it by change the out check condition. After this patch, it print: cannot allocate crashkernel (size:0x40000000) Fixes: 9c08a2a139fe ("x86: kdump: use generic interface to simplify crashke= rnel reservation code") Signed-off-by: Jinjie Ruan --- v2: - Peel off the other two patches. - Update the commit message and fix tag. --- kernel/crash_reserve.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/crash_reserve.c b/kernel/crash_reserve.c index 5b2722a93a48..5073ae205f79 100644 --- a/kernel/crash_reserve.c +++ b/kernel/crash_reserve.c @@ -421,7 +421,7 @@ void __init reserve_crashkernel_generic(char *cmdline, * For crashkernel=3Dsize[KMG],high, if the first attempt was * for high memory, fall back to low memory. */ - if (high && search_end =3D=3D CRASH_ADDR_HIGH_MAX) { + if (high && search_base =3D=3D CRASH_ADDR_LOW_MAX) { search_end =3D CRASH_ADDR_LOW_MAX; search_base =3D 0; goto retry; --=20 2.34.1