Messages in this thread | | | From | Paweł Sikora <> | Subject | Re: [2.6.38-3.x] [BUG] soft lockup - CPU#X stuck for 23s! (vfs, autofs, vserver) | Date | Mon, 24 Sep 2012 07:23:55 +0200 |
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On Sunday 23 of September 2012 18:10:30 Linus Torvalds wrote: > On Sat, Sep 22, 2012 at 11:09 PM, Paweł Sikora <pluto@pld-linux.org> wrote: > > > > br_read_lock(vfsmount_lock); > > The vfsmount_lock is a "local-global" lock, where a read-lock is > rather cheap and takes just a per-cpu lock, but the downside is that a > write-lock is *very* expensive, and can cause serious trouble. > > And the write lock is taken by the [un]mount() paths. Do *not* do > crazy things. If you do some insane "unmount and remount autofs" on a > 1s granularity, you're doing insane things. > > Why do you have that 1s timeout? Insane.
1s unmount timeout is *only* for fast bug reproduction (in few seconds after opteron startup) and testing potential patches. normally with 60s timeout it happens in few minutes..hours (depends on machine i/o+cpu load) and makes server unusable (permament soft-lockup). can we redesign vserver's mnt_is_reachable() for better locking to avoid total soft-lockup?
BR, Paweł.
ps). i'm adding Herbert to CC.
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