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bh=3OJtt0xiX5fif9iuFEdnCMWb/FO+kzZFhvV69mHkujE=; b=qB5nr1hGxRMJp5K42Q1o9VLQkUe+S2RA+Mhwnzs7h684WHWsHKYPEcQpALHoVnlWLVPzlp M7NkFFctUQkDZ4P9u+yAtfn24u1Teblk0g5octp6h9TLQxt07NE0d41Zj1+ZKEotQZPXIG rdctE91h/NSRoS47wYpjCcgNBCDzxsa1HjaHrq6ZGFJFTSix/G7iBxZp6NC/vZ9YBYySje wnTeCZMLif+mch2cQRTTl3vL2pq0chzkVBNlRvw0QVWJi2Y2WqulBQMnANqagtBgDbTmOx +PlHA2q1Stu6UOqPsyVaPA7JNBDlaFAI97acQeCFxtUt5JTtqje0o21Rv2Xjmw== From: Miquel Raynal To: David Laight Cc: Karl Mehltretter , Richard Weinberger , Vignesh Raghavendra , Andy Shevchenko , Lukas Wunner , linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mtd: cfi_cmdset_0001: shrink do_write_buffer() stack frame In-Reply-To: <20260824085632.2dd08ba9@pumpkin> (David Laight's message of "Mon, 24 Aug 2026 08:56:32 +0100") References: <20260824014703.56502-1-kmehltretter@gmail.com> <20260824085632.2dd08ba9@pumpkin> User-Agent: mu4e 1.12.12; emacs 30.2 Date: Tue, 25 Aug 2026 14:35:33 +0200 Message-ID: <87o6eqgyy2.fsf@bootlin.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Last-TLS-Session-Version: TLSv1.3 Hi David & Vignesh, On 24/08/2026 at 08:56:32 +01, David Laight = wrote: > On Mon, 24 Aug 2026 03:47:03 +0200 > Karl Mehltretter wrote: > >> arm32 allmodconfig fails to build with gcc: >>=20 >> drivers/mtd/chips/cfi_cmdset_0001.c:1883:1: error: the frame size of 1= 296 >> bytes is larger than 1280 bytes [-Werror=3Dframe-larger-than=3D] >>=20 >> With MTD_MAP_BANK_WIDTH_32 a map_word is 32 bytes, and with KASAN_STACK >> every temporary gets its own redzoned slot. do_write_buffer() builds a >> map_word for each of the twelve commands it issues, and those temporaries >> dominate its frame. > > Looks to me like pretty much all of mtd/map.h should be real functions > and not #defines or inlines. > > The bloat from all those expansions is going to be significant. > They only time they get optimised to anything small is when only > CONFIG_MTD_MAP_BANK_WIDTH_1 is set. > > The execution time of all those that do real io (especially reads) > will be dominated by the io access itself. David, may I ask if you acknowledge the fix? Vignesh, same question, maybe you also test that there is no apparent regression? Thanks, Miqu=C3=A8l