Messages in this thread | | | Date | Sat, 2 May 2020 11:31:05 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH] kernel/sys: do not use tasklist_lock to set/get scheduling priorities |
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On Fri, May 01, 2020 at 08:05:39PM -0700, Davidlohr Bueso wrote: > For both setpriority(2) and getpriority(2) there's really no need > to be taking the tasklist_lock at all - for which both share it > for the entirety of the syscall. The tasklist_lock does not protect > reading/writing the p->static_prio and task lookups are already rcu > safe, providing a stable pointer.
RCU-safe, as in, it will not crash.. However, without tasklist_lock the thread iterations (for PRIO_PGRP/PRIO_USER) now race against fork().
That is a user observable change in behaviour.
Do we care about it? No idea, and your Changelog also doesn't provide clue.
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