From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 625CC72612; Wed, 13 Aug 2025 13:45:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755092732; cv=none; b=jYnI5fduAAW++GgAgtrvms1A+8HJ+g1+1JAmg/kEqrFgcSUVIPW7pmGEB7d9JgIwrH5LdFN3CRUXZwH1hYuoDQnEmKZuPez79rqbm9u67hwLGORDy0i7kPw0LV+A4BNPmdfUOgBzJCwYG+brde2JqSBevtQ+qHOO/Bfdf9xR+lM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755092732; c=relaxed/simple; bh=D0xx7031UZevoMdpdp6ryj7WTHkAul4ivyREJrKlUK4=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=CrtNoVW54oYQrvC+uMm+8b39FxOIQYB2ZyP7VWymwFoCfhFdgbKz76YGT0q4w089tzctwNC7SoadVKRL/faD0vU5YLdcVjz52twC2h6HX4qOHtiBCNBvizCzjZmhUINjW1sWaSwpKiWvmvtPo8WITBNmmSRKbaOU3kdERTdRf4M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=lZX7OAEO; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="lZX7OAEO" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 29E37C4CEEB; Wed, 13 Aug 2025 13:45:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1755092731; bh=D0xx7031UZevoMdpdp6ryj7WTHkAul4ivyREJrKlUK4=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=lZX7OAEO4iV5S1+YXwOnpNeXysrLeSryC2YE5VkGmWFuQ1wIf+WHQIRsPfY64kEvv QzcQMAowqKlFIJSrHE1eEuBK6vW1P1AekwkoCcjrd4HOlzlC6jenE3ECVGpLYdDivk qyjpj02i46dkWEnCNEDjQSNs/9x6Jd21DB4k9HTMhz5nsiU0DfPOYMHteLZ1wJLASP qpUPUOOVkMdmZ1Z9ow7qaMytrTTWQK6SBmBQ51D/RRDYYx10iAwqrguOIiiU8j9v8N 4iS480IBHW3v/cY6/gPBGGopu5lpSm9aIIhXlxXD27EoChcg/w8dp4NObDJYFg5pZk akcmTCNvjNGFA== From: Pratyush Yadav To: Mike Rapoport Cc: Andrew Morton , Alexander Graf , Baoquan He , Changyuan Lyu , Pasha Tatashin , Pratyush Yadav , Shuah Khan , Thomas Weischuh , kexec@lists.infradead.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH 1/3] kho: allow scratch areas with zero size In-Reply-To: <20250811082510.4154080-2-rppt@kernel.org> References: <20250811082510.4154080-1-rppt@kernel.org> <20250811082510.4154080-2-rppt@kernel.org> Date: Wed, 13 Aug 2025 15:45:29 +0200 Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain On Mon, Aug 11 2025, Mike Rapoport wrote: > From: "Mike Rapoport (Microsoft)" > > Parsing of kho_scratch parameter treats zero size as an invalid value, > although it should be fine for user to request zero sized scratch area > for some types if scratch memory, when for example there is no need to > create scratch area in the low memory. Can the system boot with 0 per-node memory? If not, then perhaps we should only allow lowmem scratch to be zero? > > Treat zero as a valid value for a scratch area size but reject > kho_scratch parameter that defines no scratch memory at all. > > Signed-off-by: Mike Rapoport (Microsoft) > --- > kernel/kexec_handover.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/kernel/kexec_handover.c b/kernel/kexec_handover.c > index e49743ae52c5..c6ac5a5e51cb 100644 > --- a/kernel/kexec_handover.c > +++ b/kernel/kexec_handover.c > @@ -385,6 +385,7 @@ static int __init kho_parse_scratch_size(char *p) > { > size_t len; > unsigned long sizes[3]; > + size_t total_size = 0; > int i; > > if (!p) > @@ -421,11 +422,15 @@ static int __init kho_parse_scratch_size(char *p) > } > > sizes[i] = memparse(p, &endp); > - if (!sizes[i] || endp == p) > + if (endp == p) > return -EINVAL; > p = endp; > + total_size += sizes[i]; > } > > + if (!total_size) > + return -EINVAL; > + Looks good. BTW, unrelated to this patch, but should we also check that p == '\0' here to make sure the whole argument was consumed? > scratch_size_lowmem = sizes[0]; > scratch_size_global = sizes[1]; > scratch_size_pernode = sizes[2]; -- Regards, Pratyush Yadav