From: Giorgi Tchankvetadze <giorgitchankvetadze1997@gmail.com>
To: David Hildenbrand <david@redhat.com>,
Chaitanya S Prakash <chaitanyas.prakash@arm.com>,
linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Cc: Ryan Roberts <ryan.roberts@arm.com>,
Yang Shi <yang@os.amperecomputing.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Kevin Brodsky <kevin.brodsky@arm.com>,
Anshuman Khandual <anshuman.khandual@arm.com>,
Andrew Morton <akpm@linux-foundation.org>,
Zhenhua Huang <quic_zhenhuah@quicinc.com>,
Joey Gouly <joey.gouly@arm.com>
Subject: Re: [PATCH 2/2] arm64/mm: Update create_kpti_ng_temp_pgd() to handle pgtable_alloc failure
Date: Tue, 19 Aug 2025 12:44:09 +0400 [thread overview]
Message-ID: <17e83e3c-1314-4198-82eb-ffc18454e344@gmail.com> (raw)
In-Reply-To: <4289fc02-8e09-4d33-a4a1-0e4b268b008c@redhat.com>
Smart! BUG_ON() ends up in the generic “kernel bug” path, which on many
distros is configured to continue after printing the back-trace (e.g.
panic_on_oops=0).
Since a memory-allocation failure in early boot is unrecoverable , we
must force a halt.
On 8/19/2025 11:41 AM, David Hildenbrand wrote:
> On 13.08.25 16:56, Chaitanya S Prakash wrote:
>> create_kpti_ng_temp_pgd() was created as an alias for void returning
>> __create_pgd_mapping_locked() and relied on pgtable_alloc() to BUG_ON()
>> if an allocation failure occurred. But as __create_pgd_mapping_locked()
>> has been updated as a part of the error propagation patch to return a
>> non-void value, update create_kpti_ng_temp_pgd() to act as a wrapper
>> around __create_pgd_mapping_locked() and BUG_ON() on ret being a non
>> zero value.
>
> If my memory serves me right, panic() is preferred in such unexpected
> early-boot scenarios (BUG_ON is frowned upon), where you can actually
> print what is going wrong.
prev parent reply other threads:[~2025-08-19 9:20 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-08-13 14:56 [PATCH 0/2] arm64/mm: prevent panic on -ENOMEM in arch_add_memory() Chaitanya S Prakash
2025-08-13 14:56 ` [PATCH 1/2] arm64/mm: Allow __create_pgd_mapping() to propagate pgtable_alloc() errors Chaitanya S Prakash
2025-08-14 16:22 ` Jonathan Cameron
2025-08-15 7:30 ` Dev Jain
2025-08-15 12:12 ` Kevin Brodsky
2025-08-13 14:56 ` [PATCH 2/2] arm64/mm: Update create_kpti_ng_temp_pgd() to handle pgtable_alloc failure Chaitanya S Prakash
2025-08-15 12:00 ` Kevin Brodsky
2025-08-19 7:41 ` David Hildenbrand
2025-08-19 8:44 ` Giorgi Tchankvetadze [this message]
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