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From: "Paul E. McKenney" <paulmck@kernel.org>
To: liam.howlett@oracle.com, willy@infradead.org,
	walken.cr@gmail.com, mhocko@suse.com, hannes@cmpxchg.org
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Memory allocation on speculative fastpaths
Date: Tue, 3 May 2022 08:59:13 -0700	[thread overview]
Message-ID: <20220503155913.GA1187610@paulmck-ThinkPad-P17-Gen-1> (raw)

Hello!

Just following up from off-list discussions yesterday.

The requirements to allocate on an RCU-protected speculative fastpath
seem to be as follows:

1.	Never sleep.
2.	Never reclaim.
3.	Leave emergency pools alone.

Any others?

If those rules suffice, and if my understanding of the GFP flags is
correct (ha!!!), then the following GFP flags should cover this:

	__GFP_NOMEMALLOC | __GFP_NOWARN

Or is this just a fancy way of always returning NULL or some such?  ;-)

							Thanx, Paul

             reply	other threads:[~2022-05-03 15:59 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-05-03 15:59 Paul E. McKenney [this message]
2022-05-03 16:04 ` Memory allocation on speculative fastpaths Michal Hocko
2022-05-03 16:39   ` Paul E. McKenney
2022-05-03 18:28     ` Matthew Wilcox
2022-05-03 23:15       ` Suren Baghdasaryan
2022-05-03 23:45         ` Michal Hocko
2022-05-04  0:22           ` Matthew Wilcox
2022-05-04 16:23         ` Johannes Weiner
2022-05-24 20:37           ` Vlastimil Babka
2022-05-25 13:12             ` Johannes Weiner
2022-05-04  8:20       ` Michel Lespinasse
2022-05-04 16:52         ` Matthew Wilcox

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