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b=k2cjfhQlsWoad5+rMzaZy8ggV3Odyw3y4BjMnIu42LamZXzR0SQ4R/81v/w7NKUw3 R8zalHODDkd4snvoTZhKcKm5bvUfte25RRyb4DmJScUM/I60BYamJge0FfveuauKxF a/v7LuZXp6Drt4W1nEMlgrsP8fDvjNygEclAvjciesuMQUdspxcR1BYTcsL4A/QEyb xraIz72Q3bDwp6nSJEsV7WwZYGf2RZHSvkqIaW//GaMqPhx2FbZJPFZCeqVsTX504y +Z4V5Ka6qnkrIC7hN/ZdX4eVW7OUZs6S/Cq3kdWiHXiM0iM6IhRWwoaglPWgPeVX1k YGjiefOKIcafw== Date: Fri, 10 Jan 2025 12:15:31 +0200 From: Mike Rapoport To: Andrew Morton Cc: Guo Weikang , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v8] mm/memblock: Add memblock_alloc_or_panic interface Message-ID: References: <20250102072528.650926-1-guoweikang.kernel@gmail.com> <20250102150835.776fe72f565cc3232d83e6a7@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250102150835.776fe72f565cc3232d83e6a7@linux-foundation.org> X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: C6CE24000A X-Stat-Signature: pk5ahmnyxhjcnrm8tkp6hc5js3iizyyd X-Rspam-User: X-HE-Tag: 1736504143-88551 X-HE-Meta: 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 WG9d9NG5 sF0ShCTp675nJ2YpKNw3BkT073TXKnOTuy63/mAFuAyRu0EaM+bzECs7fvAELXgxOVVXjqz7Zh7R4/acDFUUVlc4Mlld8yxBEXeiahaVDEa6Z+eR2W9gdfwHlp7hE6ZYIc2gEeXeR4LlFKOTK6HCzW3TVu2u2c3x9CVw0m6rYitf15dp6J4wztaxxGARmQuevq9blY7X4zw/FD9PJaqtJjx8uMxgfy0Y8h8oJgEf2DPsx7lW+TMtCTwsZY0l5i7RsVJONaWQX+ywJ9zG0cFneGZzx1H7nuiL8i/T1uDfEVnkCeP8bfHKUCeLxYT6Unv5MlHuyZRsiWnxD4FNcxoKROxxFrUUTWG5Fp82D74h5K7INgrqe3RJYG3Kj/hV01+8ipcdas0sLGLZl//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: List-Subscribe: List-Unsubscribe: Hi Andrew, On Thu, Jan 02, 2025 at 03:08:35PM -0800, Andrew Morton wrote: > On Thu, 2 Jan 2025 15:25:28 +0800 Guo Weikang wrote: > > > Before SLUB initialization, various subsystems used memblock_alloc to > > allocate memory. In most cases, when memory allocation fails, an immediate > > panic is required. To simplify this behavior and reduce repetitive checks, > > introduce `memblock_alloc_or_panic`. This function ensures that memory > > allocation failures result in a panic automatically, improving code > > readability and consistency across subsystems that require this behavior. > > Just to be annoying... > > We now have many more calls to memblock_alloc_or_panic() than to > memblock_alloc(). So perhaps memblock_alloc() should default to > panicing and we add a new memblock_alloc_no_panic() for the exceptional > cases. I'd prefer the API to be explicit about what it does. memblock_alloc_or_panic() is indeed longer, but it emphasizes what it does, while memblock_alloc() that panics does not. I also wouldn't want to duplicate all memblock_alloc* with _panic or _nopanic versions. > And from looking around a bit, I think many of the remaining calls to > memblock_alloc() could be made to panic on failure anyway. If the > kernel cannot successfully execute memblock_alloc(small amount) at > __init time then the kernel is hopelessly broken and there's no point > in proceeding? > > In fact I wonder if there is really any legitimate use of > memblock_alloc_no_panic()? At the very least the caller has more context and can print something more descriptive than "failed to allocate X bytes". And I think sometimes the boot can continue with reduced functionality. I don't have examples with memblock_alloc() from the top of my head, but e.g. failure to reserve crash kernel is really not a fatal error. -- Sincerely yours, Mike.