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Thu, 27 Oct 2022 07:32:26 -0700 (PDT) X-Gm-Message-State: ACrzQf3DH/p/ZcqNBThw0uAUvuRuwZ2IwLbShNpNPtboKweBkXw8BAXM 1y6Y5lRmCRsjh2kW5Z1SyXvYFqL4a48PXMhDiZc= X-Google-Smtp-Source: AMsMyM4tqsHTbHWe+6yz0cnG9uKVuvy2JEqtwziNTOAmy0shG5LX1mgNgc+M3G+YmcTGs8ePnEbYIasezCTtPb52hqI= X-Received: by 2002:aca:bbd4:0:b0:353:f167:6fd3 with SMTP id l203-20020acabbd4000000b00353f1676fd3mr5067095oif.287.1666881145769; Thu, 27 Oct 2022 07:32:25 -0700 (PDT) MIME-Version: 1.0 References: <20221024212144.2852069-1-glider@google.com> <20221024212144.2852069-3-glider@google.com> In-Reply-To: <20221024212144.2852069-3-glider@google.com> From: Masahiro Yamada Date: Thu, 27 Oct 2022 23:31:49 +0900 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH 3/5] Kconfig.debug: disable CONFIG_FRAME_WARN for KMSAN by default To: Alexander Potapenko Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Andrew Morton , Kees Cook , Nick Desaulniers , linux-kbuild@vger.kernel.org Content-Type: text/plain; charset="UTF-8" ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1666881168; a=rsa-sha256; cv=none; b=MwM7gK/7PaqL+cYzCfIXG7kBXg54aRdRxcteBXDHtPjiruX/lnXVEsIEfpBJBcX5rwlr+K GZRjXGEXA8600jMGUD+EMmV9XEyVUkrbWv34kBepK8alfUPVAAT9GxvSlNIzZKZ0w7+wUA 9ncvCE2ndZFUnFixPXw2kPvt8wD0ZB4= ARC-Authentication-Results: i=1; imf12.hostedemail.com; dkim=pass header.d=nifty.com header.s=dec2015msa header.b=cEMOUuGR; spf=softfail (imf12.hostedemail.com: 210.131.2.81 is neither permitted nor denied by domain of masahiroy@kernel.org) smtp.mailfrom=masahiroy@kernel.org; dmarc=fail reason="No valid SPF, DKIM not aligned (relaxed)" header.from=kernel.org (policy=none) ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1666881168; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=4HDEXnWr6VYARBxhtIHHxyW+0nXTxgQlhNlzoM6U/Ls=; b=7dJcGAI6RSTPHuOEYLUf1Ftr4rW/hZgPRb7kD4JEHd+gtfof3SHrDCDXZzZ+YBCDE7K64p AwwhwJbdedu0EgTJTwQB29viAUVxmOcImu4NTfngOdFDcy5qBGBRn5vmN5RRZSXLQSuzfl ivGt1LbfdwXzeS7ac4Uo06TwfFF57Jw= X-Stat-Signature: n3dch51mppf5uyw973f7xz97nmk79s6c X-Rspamd-Queue-Id: 378E840034 Authentication-Results: imf12.hostedemail.com; dkim=pass header.d=nifty.com header.s=dec2015msa header.b=cEMOUuGR; spf=softfail (imf12.hostedemail.com: 210.131.2.81 is neither permitted nor denied by domain of masahiroy@kernel.org) smtp.mailfrom=masahiroy@kernel.org; dmarc=fail reason="No valid SPF, DKIM not aligned (relaxed)" header.from=kernel.org (policy=none) X-Rspam-User: X-Rspamd-Server: rspam05 X-HE-Tag: 1666881166-697795 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 Tue, Oct 25, 2022 at 6:22 AM Alexander Potapenko wrote: > > KMSAN adds a lot of instrumentation to the code, which results in > increased stack usage (up to 2048 bytes and more in some cases). > It's hard to predict how big the stack frames can be, so we disable > the warnings for KMSAN instead. > > Cc: Andrew Morton > Cc: Kees Cook > Cc: Masahiro Yamada > Cc: Nick Desaulniers > Cc: linux-kbuild@vger.kernel.org > Link: https://github.com/google/kmsan/issues/89 > Signed-off-by: Alexander Potapenko > --- > lib/Kconfig.debug | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug > index 3fc7abffc7aa2..29280072dc0e4 100644 > --- a/lib/Kconfig.debug > +++ b/lib/Kconfig.debug > @@ -400,8 +400,9 @@ config FRAME_WARN > default 1536 if (!64BIT && XTENSA) > default 1024 if !64BIT > default 2048 if 64BIT > + default 0 if KMSAN This is wrong. Kconfig picks up the first default entry which has true 'if' condition. Since (!64BIT || 64BIT) covers all the possible cases, this patch is just adding dead code. > help > - Tell gcc to warn at build time for stack frames larger than this. > + Tell the compiler to warn at build time for stack frames larger than this. > Setting this too low will cause a lot of warnings. > Setting it to 0 disables the warning. > > -- > 2.38.0.135.g90850a2211-goog > -- Best Regards Masahiro Yamada