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* [Ksummit-discuss] [TECH TOPIC] Beyond per-CPU atomics and rseq syscall: thoroughly abusing mm with the do_on_cpu syscall
@ 2019-07-08 21:06 Mathieu Desnoyers
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From: Mathieu Desnoyers @ 2019-07-08 21:06 UTC (permalink / raw)
  To: ksummit-discuss

The Restartable Sequences system call [1,2,3,4] introduced in Linux 4.18
has limitations which can be solved by introducing a bytecode
interpreter running in inter-processor interrupt context which accesses
user-space data.

However, there are a handful of reasons why accessing user-space
data from an IPI handler concurrently with user-space execution
is a bad idea, starting with page fault handling. This discussion
aims at gathering feedback from the mm community on the do_on_cpu
system call aiming to solve this gracefully.

[1] "PerCpu Atomics" http://www.linuxplumbersconf.org/2013/ocw/system/presentations/1695/original/LPC%20-%20PerCpu%20Atomics.pdf
[2] "Restartable sequences" https://lwn.net/Articles/650333/
[3] "Restartable sequences restarted" https://lwn.net/Articles/697979/
[4] "Restartable sequences and ops vectors" https://lwn.net/Articles/737662/

Thanks,

Mathieu

-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com

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2019-07-08 21:06 [Ksummit-discuss] [TECH TOPIC] Beyond per-CPU atomics and rseq syscall: thoroughly abusing mm with the do_on_cpu syscall Mathieu Desnoyers

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