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Wed, 19 Jun 2024 08:30:46 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id Pgs7IzaXcmbgHQAAD6G6ig (envelope-from ); Wed, 19 Jun 2024 08:30:46 +0000 Date: Wed, 19 Jun 2024 10:30:46 +0200 From: Michal Hocko To: Shakeel Butt Cc: Andrew Morton , Linus Torvalds , kernel-team@meta.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Kyle McMartin Subject: Re: [PATCH] mm: ratelimit oversized kvmalloc warnings instead of once Message-ID: References: <20240618213421.282381-1-shakeel.butt@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: 63548A0007 X-Stat-Signature: ra5s6ogh6w7hdn5jpo5jbp9kuwocdthu X-Rspamd-Server: rspam09 X-Rspam-User: X-HE-Tag: 1718785848-871796 X-HE-Meta: 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 apgyYoDb FlnSuZeZoWkRzCq6edsX+qeNKC3B7UtDpTvfW+H5fvGJ/bIsORmqWaIgOx5vsKZsw0j7edO68yTvT27NOYJ9v3geQHiElhuUyioBFYBG2YsOBM7QwYntTEsu4ICmYPPLz/BfGTtRtLUrRSHSNkUHoGjMZ7DXfPXK11J5bPjBPDn7UPC5k7XyzZbLQx1HwYEMC3tTUftzzk6USpxCiKhNm4JgOF0SJpkr1WHIEC6ufC85bwMHYgSdM/NK+mUQUSFDiFIELNEbbc7IlauzxffYfcONPOFfXIptN5ifhUGCY5RWP+DyKMeKtfb/zQA== 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 Wed 19-06-24 01:03:16, Shakeel Butt wrote: > On Wed, Jun 19, 2024 at 09:19:41AM GMT, Michal Hocko wrote: > > On Tue 18-06-24 14:34:21, Shakeel Butt wrote: > > > At the moment oversize kvmalloc warnings are triggered once using > > > WARN_ON_ONCE() macro. One issue with this approach is that it only > > > detects the first abuser and then ignores the remaining abusers which > > > complicates detecting all such abusers in a timely manner. The situation > > > becomes worse when the repro has low probability and requires production > > > traffic and thus require large set of machines to find such abusers. In > > > Mera production, this warn once is slowing down the detection of these > > > abusers. Simply replace WARN_ON_ONCE with WARN_RATELIMIT. > > > > Long time ago, I've had a patch to do the once_per_callsite WARN. I > > cannot find reference at the moment but it used stack depot to note > > stacks that have already triggered. Back then there was no reponse on > > the ML. Should I try to dig deep and recover it from my archives? I > > think this is exactly kind of usecase where it would fit. > > > > Do you mean something like warn once per unique call stack? Exactly! > If yes then > I think that is better than the simple ratelimiting version as > ratelimiting one may still miss some abusers and also may keep warning > about the same abuser. Please do share your patch. https://lore.kernel.org/all/20170103134424.28123-1-mhocko@kernel.org/ -- Michal Hocko SUSE Labs