Messages in this thread | | | Date | Wed, 17 Jun 2020 05:23:21 -0700 | From | Matthew Wilcox <> | Subject | Re: [PATCH v4 0/3] mm, treewide: Rename kzfree() to kfree_sensitive() |
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On Wed, Jun 17, 2020 at 01:31:57PM +0200, Michal Hocko wrote: > On Wed 17-06-20 04:08:20, Matthew Wilcox wrote: > > If you call vfree() under > > a spinlock, you're in trouble. in_atomic() only knows if we hold a > > spinlock for CONFIG_PREEMPT, so it's not safe to check for in_atomic() > > in __vfree(). So we need the warning in order that preempt people can > > tell those without that there is a bug here. > > ... Unless I am missing something in_interrupt depends on preempt_count() as > well so neither of the two is reliable without PREEMPT_COUNT configured.
preempt_count() always tracks whether we're in interrupt context, regardless of CONFIG_PREEMPT. The difference is that CONFIG_PREEMPT will track spinlock acquisitions as well.
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