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Mon, 05 Aug 2024 07:06:09 -0700 (PDT) Received: from localhost ([183.226.244.186]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-7106ed2d029sm5435082b3a.199.2024.08.05.07.06.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 05 Aug 2024 07:06:09 -0700 (PDT) From: chenqiwu X-Google-Original-From: chenqiwu Date: Mon, 5 Aug 2024 22:06:01 +0800 To: Marco Elver Cc: chenqiwu , glider@google.com, dvyukov@google.com, akpm@linux-foundation.org, kasan-dev@googlegroups.com, linux-mm@kvack.org Subject: Re: [PATCH] mm: kfence: print the age time for alloacted objectes to trace memleak Message-ID: <20240805140601.GA2811@rlk> References: <20240803133608.2124-1-chenqiwu@xiaomi.com> <20240804034607.GA11291@rlk> <20240805033534.GA15091@rlk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 5237016002A X-Stat-Signature: mr6fs6cmke1hhrbia7umkip7um1onqqe X-Rspam-User: X-HE-Tag: 1722866771-391158 X-HE-Meta: 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 ClOFK13m BPg/apnz8+i2Sg4sWNa1Drd3DRHWn57V/IApDt4D51w3iLvykwJYuiA9jYr9TM1F5RqWLf1tpM/saQsnb/qz1T6dXrm0WVPrSRPlXNAkyYgQ1YZd3FHe2hXgE51A4wfqpV+Ldw+g2l/FzrxU5tRx4yBFfCQFgXwHJt9R1XFA99d+sKnrBkdg5m/DsqaNQF1KHP+Ym3btxGk85XYPvAuCSqvok9tn1Zop/TIJYn6onPw/KKE0cSoQr6+eqP9QjQBhA9t6QcOkxsVrFbWCT4pmKChjYhItaGz4tK84RSpmcE/fATKDMtlmjTRLjhu7HgMPG2lHbWSldzW7SNNRVKEHwLphD/68c7dnqjDk/7d4o5STD4Ex0KXxOir2T0g== X-Bogosity: Ham, tests=bogofilter, spamicity=0.352684, 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 Mon, Aug 05, 2024 at 08:50:57AM +0200, Marco Elver wrote: > > The "allocated/freed" info is superfluous, as freed objects will have > a free stack. > > Consider a slightly better script vs. just using grep. Well, I think using grep is eaiser than a script to find leaks by a large number of alloc tracks. > /sys/kernel/debug/kfence/objects is of secondary concern and was added > primarily as a debugging aid for KFENCE developers. We never thought > it could be used to look for leaks, but good you found another use for > it. ;-) > The priority is to keep regular error reports generated by KFENCE > readable. Adding this "allocated/freed" info just makes the line > longer and is not useful. > How about print meta->state directly to get the object state for its alloc/free track? - seq_con_printf(seq, "%s by task %d on cpu %d at %lu.%06lus:\n", + seq_con_printf(seq, "%s by task %d on cpu %d at %lu.%06lus (%lu.%06lus ago) state %d:\n", show_alloc ? "allocated" : "freed", track->pid, - track->cpu, (unsigned long)ts_sec, rem_nsec / 1000); + track->cpu, (unsigned long)ts_sec, rem_nsec / 1000, + (unsigned long)interval_nsec, rem_interval_nsec / 1000, + meta->state); > I'm happy with the "(%lu.%06lus ago)" part alone. If it's still a not good idea, I will follow your suggestion and resend it as v2. Thanks Qiwu