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([103.163.65.25]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-34e70dccd14sm35760786a91.16.2025.12.31.04.21.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 31 Dec 2025 04:21:23 -0800 (PST) From: Dipendra Khadka To: akpm@linux-foundation.org Cc: kdipendra88@gmail.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, mhocko@suse.com, rientjes@google.com, shakeel.butt@linux.dev Subject: Re: [PATCH] mm/oom_kill: Remove unnecessary integer promotion in format string Date: Wed, 31 Dec 2025 12:21:17 +0000 Message-ID: <20251231122117.7683-1-kdipendra88@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20251230123336.ef33f8a55df71f3e3f782532@linux-foundation.org> References: <20251230123336.ef33f8a55df71f3e3f782532@linux-foundation.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam02 X-Stat-Signature: q9farj5pgcranurm5c37dh6szjw7ftm8 X-Rspam-User: X-Rspamd-Queue-Id: 8858A80003 X-HE-Tag: 1767183684-24082 X-HE-Meta: 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 0tKbNCKU 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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: >It's a teeny issue but I do like the present code - be very explicit >and careful about the types we're dealing with, don't rely on unobvious >C rules. Actually, the scenario here is that while printing a short, it is **promoted** to int due to C's variadic argument promotion rules. Yes, we must use %hd when the **semantic type** is short. However, due to integer promotion, the value is already passed as a 4-byte int on the stack. The %hd format specifier then casts it back to short for display. Since the value is already promoted to int internally, using %d is simpler and avoids the unnecessary cast. The checkpatch warning confirms this: ``` WARNING: Integer promotion: Using 'h' in '%hd' is unnecessary #461: FILE: mm/oom_kill.c:461: + pr_warn("%s invoked oom-killer: gfp_mask=%#x(%pGg), order=%d, oom_score_adj=%hd\n", + current->comm, oc->gfp_mask, &oc->gfp_mask, oc->order, + current->signal->oom_score_adj); WARNING: Integer promotion: Using 'h' in '%hd' is unnecessary #961: FILE: mm/oom_kill.c:961: + pr_err("%s: Killed process %d (%s) total-vm:%lukB, anon-rss:%lukB, file-rss:%lukB, shmem-rss:%lukB, UID:%u pgtables:%lukB oom_score_adj:%hd\n", + message, task_pid_nr(victim), victim->comm, K(mm->total_vm), + K(get_mm_counter(mm, MM_ANONPAGES)), + K(get_mm_counter(mm, MM_FILEPAGES)), + K(get_mm_counter(mm, MM_SHMEMPAGES)), + from_kuid(&init_user_ns, task_uid(victim)), + mm_pgtables_bytes(mm) >> 10, victim->signal->oom_score_adj); ``` Checkpatch flags the 'h' modifier as unnecessary for this reason, and many other subsystems have moved to using %d for promoted types. Hence, I think this patch aligns with kernel coding practices. Best Rgards, Dipendra Khadka