lkml.org 
[lkml]   [2019]   [Aug]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [patch V2 0/7] fs: Substitute bit-spinlocks for PREEMPT_RT and debugging
On Thu, Aug 08, 2019 at 09:02:47AM +0200, Thomas Gleixner wrote:
> > > mm/slub.c: bit_spin_lock(PG_locked, &page->flags);
> >
> > One caller ouf of a gazillion that spins on the page lock instead of
> > sleepign on it like everyone else. That should not have passed your
> > smell test to start with :)
>
> I surely stared at it, but that cannot sleep. It's in the middle of a
> preempt and interrupt disabled region and used on architectures which do
> not support CMPXCHG_DOUBLE and ALIGNED_STRUCT_PAGE ...

I know. But the problem here is that normally PG_locked is used together
with wait_on_page_bit_*, but this one instances uses the bit spinlock
helpers. This is the equivalent of calling spin_lock on a struct mutex
rather than having a mutex_lock_spin helper for this case. Does SLUB
work on -rt at all?

\
 
 \ /
  Last update: 2019-08-08 09:31    [W:0.201 / U:0.020 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site