Date: Wed, 29 Nov 2017 16:33:50 +0100 From: Hans Petter Selasky <hps@selasky.org> To: John Baldwin <jhb@freebsd.org>, Nathan Whitehorn <nwhitehorn@freebsd.org> Cc: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org, Konstantin Belousov <kib@FreeBSD.org>, "O. Hartmann" <ohartmann@walstatt.org>, KrishnamRaju ErapaRaju <Krishna2@chelsio.com> Subject: Re: svn commit: r326218 - head/sys/kern Message-ID: <2e752d6a-d34a-dde0-acea-fdbf8bebea51@selasky.org> In-Reply-To: <14058479.lc6xlYgyBM@ralph.baldwin.cx> References: <201711252341.vAPNf5Qx001464@repo.freebsd.org> <14322447.103fKFTi3y@ralph.baldwin.cx> <3fc45d5f-22b9-0562-278b-c515e36f48e7@freebsd.org> <14058479.lc6xlYgyBM@ralph.baldwin.cx>
next in thread | previous in thread | raw e-mail | index | archive | help
Hi Nathan,
The chunk below causes sched_pin() to stop working and should be removed
from your commit ??!!
It probably explains the hangs seen recently reported by various brave
people running 12-current :-)
Specifically I see threads migrating between CPUs when td->td_pinned > 0
using the LinuxKPI RCU API, which in turn leads to a hang when trying to
synchronize RCU.
--HPS
diff --git a/sys/kern/sched_ule.c b/sys/kern/sched_ule.c
index 5c8bae5afa1..bd4b505f6c3 100644
--- a/sys/kern/sched_ule.c
+++ b/sys/kern/sched_ule.c
@@ -2453,7 +2453,7 @@ sched_add(struct thread *td, int flags)
* Pick the destination cpu and if it isn't ours transfer to the
* target cpu.
*/
- td_get_sched(td)->ts_cpu = curcpu; /* Pick something valid to
start */
+// td_get_sched(td)->ts_cpu = curcpu; /* Pick something valid to
start */
cpu = sched_pickcpu(td, flags);
tdq = sched_setcpu(td, cpu, flags);
tdq_add(tdq, td, flags);
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?2e752d6a-d34a-dde0-acea-fdbf8bebea51>