Messages in this thread | | | Date | Thu, 31 Mar 2011 12:03:48 +0200 | Subject | Re: [tip:x86/urgent] x86, mce: Fix RCU lockdep from mce_poll() | From | Zdenek Kabelac <> |
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However on my machine - I do not a see a difference ?
I've this patch applied - and it still gives me the same error. (using 6aba74f2791287ec407e0f92487a725a25908067 and this patch)
Here are my RCU config options:
# grep RCU .config # RCU Subsystem CONFIG_TREE_PREEMPT_RCU=y CONFIG_PREEMPT_RCU=y CONFIG_RCU_TRACE=y CONFIG_RCU_FANOUT=64 # CONFIG_RCU_FANOUT_EXACT is not set CONFIG_TREE_RCU_TRACE=y CONFIG_PROVE_RCU=y # CONFIG_PROVE_RCU_REPEATEDLY is not set # CONFIG_SPARSE_RCU_POINTER is not set # CONFIG_RCU_TORTURE_TEST is not set CONFIG_RCU_CPU_STALL_DETECTOR=y CONFIG_RCU_CPU_STALL_TIMEOUT=60 CONFIG_RCU_CPU_STALL_DETECTOR_RUNNABLE=y CONFIG_RCU_CPU_STALL_VERBOSE=y
2011/3/31 tip-bot for Davidlohr Bueso <dave@gnu.org>: > Commit-ID: 706453b0d1fabf4dccbcffa29356d0dd6ab9afb9 > Gitweb: http://git.kernel.org/tip/706453b0d1fabf4dccbcffa29356d0dd6ab9afb9 > Author: Davidlohr Bueso <dave@gnu.org> > AuthorDate: Wed, 30 Mar 2011 23:13:24 -0300 > Committer: Ingo Molnar <mingo@elte.hu> > CommitDate: Thu, 31 Mar 2011 11:06:08 +0200 > > x86, mce: Fix RCU lockdep from mce_poll() > > Based on the following message: > > =================================================== > [ INFO: suspicious rcu_dereference_check() usage. ] > --------------------------------------------------- > arch/x86/kernel/cpu/mcheck/mce.c:1628 invoked > rcu_dereference_check() without protection! > > other info that might help us debug this: > > rcu_scheduler_active = 1, debug_locks = 1 > no locks held by mcelog/2350. > > stack backtrace: > Pid: 2350, comm: mcelog Tainted: G W 2.6.37-rc1+ #7 > Call Trace: > [<ffffffff8108e6d4>] lockdep_rcu_dereference+0xa4/0xc0 > [<ffffffff810189e9>] mce_poll+0xa9/0xd0 > [<ffffffff81160585>] do_sys_poll+0x275/0x550 > [<ffffffff8115f0e0>] ? __pollwait+0x0/0xf0 > [<ffffffff8115f1d0>] ? pollwake+0x0/0x60 > [<ffffffff8115f1d0>] ? pollwake+0x0/0x60 > [<ffffffff8130431c>] ? rcu_read_lock_held+0x2c/0x30 > [<ffffffff8130549a>] ? radix_tree_lookup_element+0xda/0x100 > [<ffffffff81121f08>] ? __do_fault+0x128/0x470 > [<ffffffff81100bdb>] ? filemap_fault+0xdb/0x4e0 > [<ffffffff810ffe75>] ? unlock_page+0x25/0x30 > [<ffffffff81069ddf>] ? sigprocmask+0x3f/0x100 > [<ffffffff8183672b>] ? _raw_spin_unlock_irq+0x2b/0x60 > [<ffffffff8108fefd>] ? trace_hardirqs_on_caller+0x13d/0x180 > [<ffffffff8108ff4d>] ? trace_hardirqs_on+0xd/0x10 > [<ffffffff8183672b>] ? _raw_spin_unlock_irq+0x2b/0x60 > [<ffffffff811608a7>] sys_ppoll+0x47/0x190 > [<ffffffff8108fefd>] ? trace_hardirqs_on_caller+0x13d/0x180 > [<ffffffff81835d39>] ? trace_hardirqs_on_thunk+0x3a/0x3f > [<ffffffff810030eb>] system_call_fastpath+0x16/0x1b > > This code is simply checking the value of the pointer, and > therefore need not protect any actual dereferences. Replace > rcu_dereference_check_mce() with rcu_dereference_index_check(). > > Signed-off-by: Davidlohr Bueso <dave@gnu.org> > Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> > Cc: Zdenek Kabelac <zdenek.kabelac@gmail.com> > Cc: Andi Kleen <andi@firstfloor.org> > LKML-Reference: <1301537604.2140.21.camel@offworld> > Signed-off-by: Ingo Molnar <mingo@elte.hu> > --- > arch/x86/kernel/cpu/mcheck/mce.c | 2 +- > 1 files changed, 1 insertions(+), 1 deletions(-) > > diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c > index 5a05ef6..a2d664f 100644 > --- a/arch/x86/kernel/cpu/mcheck/mce.c > +++ b/arch/x86/kernel/cpu/mcheck/mce.c > @@ -1626,7 +1626,7 @@ out: > static unsigned int mce_poll(struct file *file, poll_table *wait) > { > poll_wait(file, &mce_wait, wait); > - if (rcu_dereference_check_mce(mcelog.next)) > + if (rcu_dereference_index_check(mcelog.next, rcu_read_lock_sched_held())) > return POLLIN | POLLRDNORM; > if (!mce_apei_read_done && apei_check_mce()) > return POLLIN | POLLRDNORM; > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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