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Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1qayBr-006d0T-IK; Tue, 29 Aug 2023 12:51:27 +0000 Date: Tue, 29 Aug 2023 13:51:27 +0100 From: Matthew Wilcox To: Anshuman Khandual Cc: linux-mm@kvack.org, Andrew Morton , linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm/mmap: Tighten up cmdline_parse_stack_guard_gap() Message-ID: References: <20230828052212.748872-1-anshuman.khandual@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230828052212.748872-1-anshuman.khandual@arm.com> X-Rspamd-Queue-Id: 547E214000E X-Rspam-User: X-Stat-Signature: urzp6jeogeh63ouzkinwx7dujse5141k X-Rspamd-Server: rspam01 X-HE-Tag: 1693313493-852021 X-HE-Meta: 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 T75zEJK0 P8axwgLMeSFKwpakqSGepd5WzHizU+b5upMQG2cjNi0sLcSumutfhID0zcouMyjRdMIdEJaA/BDNl+rK5BB2XOH813HRL7PmOFSj/zAuN+aIxbhPX+v+zwz5mtjpGeCM4HILo/UF9lgmGShVTAMBFhs0JXxbTFk83F5yOA+GMJ90a8yVox9X47wWD/g== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, Aug 28, 2023 at 10:52:12AM +0530, Anshuman Khandual wrote: > -static int __init cmdline_parse_stack_guard_gap(char *p) > +static int __init cmdline_parse_stack_guard_gap(char *str) > { > unsigned long val; > - char *endptr; > > - val = simple_strtoul(p, &endptr, 10); > - if (!*endptr) > - stack_guard_gap = val << PAGE_SHIFT; > + if (!str) > + return 0; Please explain how this function can be called with a NULL pointer. > - return 1; > + val = simple_strtoul(str, &str, 10); > + if (!*str && val) { > + stack_guard_gap = val << PAGE_SHIFT; > + return 1; > + } > + return 0; > } Now you've removed the abillity for someone to say stack_guard_gap=0, which seems potentially useful.