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Tue, 15 Oct 2024 03:47:08 +0000 (UTC) Date: Tue, 15 Oct 2024 11:47:04 +0800 From: Baoquan He To: Ryan Roberts Cc: Andrew Morton , Anshuman Khandual , Ard Biesheuvel , Catalin Marinas , David Hildenbrand , Greg Marsden , Ivan Ivanov , Kalesh Singh , Marc Zyngier , Mark Rutland , Matthias Brugger , Miroslav Benes , Will Deacon , kexec@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [RFC PATCH v1 19/57] crash: Remove PAGE_SIZE compile-time constant assumption Message-ID: References: <20241014105514.3206191-1-ryan.roberts@arm.com> <20241014105912.3207374-1-ryan.roberts@arm.com> <20241014105912.3207374-19-ryan.roberts@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20241014105912.3207374-19-ryan.roberts@arm.com> X-Scanned-By: MIMEDefang 3.0 on 10.30.177.15 X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: E669A20019 X-Stat-Signature: gwi4npkdso978nt9njc5rbty8o1mg4yu X-Rspam-User: X-HE-Tag: 1728964030-755204 X-HE-Meta: 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 q1ft39Z0 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 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 10/14/24 at 11:58am, Ryan Roberts wrote: > To prepare for supporting boot-time page size selection, refactor code > to remove assumptions about PAGE_SIZE being compile-time constant. Code > intended to be equivalent when compile-time page size is active. > > Updated BUILD_BUG_ON() to test against limit. > > Signed-off-by: Ryan Roberts > --- > > ***NOTE*** > Any confused maintainers may want to read the cover note here for context: > https://lore.kernel.org/all/20241014105514.3206191-1-ryan.roberts@arm.com/ > > kernel/crash_core.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/kernel/crash_core.c b/kernel/crash_core.c > index 63cf89393c6eb..978c600a47ac8 100644 > --- a/kernel/crash_core.c > +++ b/kernel/crash_core.c > @@ -465,7 +465,7 @@ static int __init crash_notes_memory_init(void) > * Break compile if size is bigger than PAGE_SIZE since crash_notes > * definitely will be in 2 pages with that. > */ > - BUILD_BUG_ON(size > PAGE_SIZE); > + BUILD_BUG_ON(size > PAGE_SIZE_MIN); This should be OK. While one thing which could happen is if selected size is 64K, PAGE_SIZE_MIN is 4K, it will issue a false-positive warning when compiling while actual it's not a problem during running. Not sure if that could happen on arm64. Anyway, we can check the crash_notes to get why it's so big when it really happens. So, Acked-by: Baoquan He > > crash_notes = __alloc_percpu(size, align); > if (!crash_notes) { > -- > 2.43.0 > >