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Wed, 31 Jul 2024 19:44:42 +0900 (JST) (envelope-from penguin-kernel@I-love.SAKURA.ne.jp) Message-ID: <9f1d0f2b-ee22-48b7-ba60-d7b886572670@I-love.SAKURA.ne.jp> Date: Wed, 31 Jul 2024 19:44:41 +0900 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 3/4] mm: BUG_ON to avoid NULL deference while __GFP_NOFAIL fails To: Vlastimil Babka , Barry Song <21cnbao@gmail.com>, akpm@linux-foundation.org, linux-mm@kvack.org Cc: 42.hyeyoo@gmail.com, cl@linux.com, hailong.liu@oppo.com, hch@infradead.org, iamjoonsoo.kim@lge.com, lstoakes@gmail.com, mhocko@suse.com, penberg@kernel.org, rientjes@google.com, roman.gushchin@linux.dev, torvalds@linux-foundation.org, urezki@gmail.com, v-songbaohua@oppo.com, virtualization@lists.linux.dev, Kees Cook References: <20240731000155.109583-1-21cnbao@gmail.com> <20240731000155.109583-4-21cnbao@gmail.com> Content-Language: en-US From: Tetsuo Handa In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: e1n7atjaajz19micdhc6cqzbpe5ni4gj X-Rspamd-Queue-Id: 3635620011 X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1722422699-704438 X-HE-Meta: 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 DD9+RlHw IcHW4Vkc75P7MxT9Vf0TPcrXACfZfRF4/h6CmLJgOrDf101yKXpfwkz0EWKC9NXYKSzUpH0zzmwQoaif0u7Mb24+I4hu++rELMsHSPmDluvG8tMCzoxVL00irmYSfeSnfvSBx3MEr2XzxVLU7kuiBU9jxXivOXXSZGGVqWZJQP/LpbqbhEPPSqRHl79q6uVLiFxPWcb0dUBaBPbQUYkx4XuPLwNXXUvnDc+Wkdm7I9Xq5QsBRXWZACBhEz3xPhGFWTcmMZPLnaxsxPqdDZytCNbvNrznvwYXUWLhBwaEbyXUowURtUvSunODfMRRfxT9X/4C/i8Nu8BgmxevFieR3rs/P9DW6j0hAx3RRQGV16RAYJI0= 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: List-Subscribe: List-Unsubscribe: On 2024/07/31 19:29, Vlastimil Babka wrote: >> @@ -827,8 +827,10 @@ kvmalloc_array_node_noprof(size_t n, size_t size, gfp_t flags, int node) >> { >> size_t bytes; >> >> - if (unlikely(check_mul_overflow(n, size, &bytes))) >> + if (unlikely(check_mul_overflow(n, size, &bytes))) { >> + BUG_ON(flags & __GFP_NOFAIL); > > Shouldn't we produce some kind of warning also in the no-NOFAIL case? > Returning a NULL completely silently feels wrong. Doesn't embedding macros like BUG_ON() into inline functions needlessly bloat the kernel size? I think we can call a non-inlined function (that is marked as EXPORT_SYMBOL()) for emitting warning.