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From: "Alexei Starovoitov" To: "Vlastimil Babka (SUSE)" , "Harry Yoo (Oracle)" , "Matthew Wilcox" Cc: "Vlastimil Babka" , "Peter Zijlstra" , "Ingo Molnar" , "Will Deacon" , "Sebastian Andrzej Siewior" , "LKML" , "linux-mm@kvack.org" , "Linus Torvalds" , "Waiman Long" , "Mel Gorman" , "Steven Rostedt" , "Hao Li" , "Andrew Morton" , "Suren Baghdasaryan" , "Michal Hocko" , "Brendan Jackman" , "Johannes Weiner" , "Zi Yan" , "Christoph Lameter" , "David Rientjes" , "Roman Gushchin" X-Mailer: aerc 0.21.0 References: In-Reply-To: X-Rspamd-Queue-Id: 9FC8D100002 X-Stat-Signature: c85439j4uzghppi7bd66daphtjm8d1u7 X-Rspam-User: X-Rspamd-Server: rspam09 X-HE-Tag: 1776349599-905338 X-HE-Meta: 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 cB191wsw 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu Apr 16, 2026 at 3:05 AM PDT, Vlastimil Babka (SUSE) wrote: >> I think we need a special spinlock type that wraps something like this >> and use them when spinlocks can be trylock'd in an unknown context: >> pcp lock, zone lock, per-node partial slab list lock, >> per-node barn lock, etc. > > Soudns like a lot of hassle for a niche config (SMP=3Dn) where nobody wou= ld > use e.g. bpf tracing anyway. We already have this in kmalloc_nolock(): > > /* > * See the comment for the same check in > * alloc_frozen_pages_nolock_noprof() > */ > if (IS_ENABLED(CONFIG_PREEMPT_RT) && (in_nmi() || in_hardirq())) > return NULL; > > It would be trivial to extend this to !SMP. However it wouldn't cover the > kprobe context. Any idea Alexei? Yeah. Totally fine with that. Certainly better than "special spinlock type"= .