Hi Sasha and Kim, I believe Kim is right and the WARN_ON_ONCE condition should be negated. Furthermore, I'm pretty sure I'm the one to blame for this bug.
Good catch and thank you both. (Un)fortunately, I'm in a vacation in an island resort in Thailand at the moment and the beer is much better than the Internet connection. I'll do my best to prepare, test and send a patch, but if someone beats me to it before my return in 10 days I will be happy to review. Many thanks, Gilad On Aug 4, 2014 1:41 PM, "Joonsoo Kim" <iamjoonsoo....@lge.com> wrote: > > On Sun, Aug 03, 2014 at 10:57:02PM -0400, Sasha Levin wrote: > > Hi all, > > > > While fuzzing with trinity inside a KVM tools guest running the latest -next > > kernel, I've stumbled on the following spew: > > > > > > [ 1226.701012] WARNING: CPU: 6 PID: 8624 at kernel/smp.c:673 > > on_each_cpu_cond+0x27f/0x2f0() > > [ 1226.703128] Modules linked in: > > [ 1226.703955] CPU: 6 PID: 8624 Comm: trinity-c26 Tainted: G W > > 3.16.0-rc7-next-20140801-sasha-00047-gd6ce559 #991 > > [ 1226.706792] ffff881b2e8a3000 0000000023830039 0000000000000000 > > ffff881b2e8a3000 > > [ 1226.708179] ffff881ada5b3978 ffffffffa1ee96b4 0000000000000000 > > ffff881ada5b39b8 > > [ 1226.709610] ffffffff9d1ce5ba ffffffff9d2c0ddf 000000000000001b > > ffff8807d7608000 > > [ 1226.710966] Call Trace: > > [ 1226.711417] dump_stack (lib/dump_stack.c:52) > > [ 1226.712311] warn_slowpath_common (kernel/panic.c:432) > > [ 1226.715425] warn_slowpath_null (kernel/panic.c:466) > > [ 1226.716436] on_each_cpu_cond (kernel/smp.c:673 (discriminator 3)) > > [ 1226.720821] __kmem_cache_shrink (mm/slub.c:3420) > > [ 1226.722711] slab_memory_callback (mm/slub.c:3464 mm/slub.c:3556) > > [ 1226.723925] notifier_call_chain (kernel/notifier.c:93) > > [ 1226.725244] __blocking_notifier_call_chain (kernel/notifier.c:319) > > [ 1226.726310] blocking_notifier_call_chain (kernel/notifier.c:329) > > [ 1226.727263] memory_notify (drivers/base/memory.c:177) > > [ 1226.728210] __offline_pages.constprop.23 (include/linux/notifier.h:179 > > mm/memory_hotplug.c:1682) > > [ 1226.731896] offline_pages (mm/memory_hotplug.c:1787) > > [ 1226.733095] memory_subsys_offline (drivers/base/memory.c:267 > > drivers/base/memory.c:304) > > [ 1226.735208] device_offline (drivers/base/core.c:1428) > > [ 1226.736966] online_store (drivers/base/core.c:451 (discriminator 2)) > > [ 1226.737720] dev_attr_store (drivers/base/core.c:138) > > [ 1226.739986] sysfs_kf_write (fs/sysfs/file.c:116) > > [ 1226.742105] kernfs_fop_write (fs/kernfs/file.c:308) > > [ 1226.743058] do_loop_readv_writev (fs/read_write.c:708) > > [ 1226.745095] do_readv_writev (fs/read_write.c:840) > > [ 1226.752769] vfs_writev (fs/read_write.c:879) > > [ 1226.753755] SyS_writev (fs/read_write.c:911 fs/read_write.c:903) > > [ 1226.754660] tracesys (arch/x86/kernel/entry_64.S:541) > > > > No time to dig too much into this today, will work on it tomorrow. > > I think that that WARN_ON_ONCE() in kernel/smp.c:673 is wrong. > smp_call_function_single() returns 0 if success so it should be > WARN_ON_ONCE(ret) rather than WARN_ON_ONCE(!ret). > > Thanks. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/