Messages in this thread | | | Date | Thu, 28 Sep 2017 18:18:50 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH v3 tip/core/rcu 40/40] rcu: Make non-preemptive schedule be Tasks RCU quiescent state |
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On Thu, Sep 28, 2017 at 09:05:14AM -0700, Paul E. McKenney wrote: > > do_async_page_fault+0x72/0x90 arch/x86/kernel/kvm.c:271 > > async_page_fault+0x22/0x30 arch/x86/entry/entry_64.S:1069 > > RIP: 0010:format_decode+0x240/0x830 lib/vsprintf.c:1996 > > RSP: 0018:ffff88003b2df520 EFLAGS: 00010283 > > RAX: 000000000000003f RBX: ffffffffb5d1e141 RCX: ffff88003b2df670 > > RDX: 0000000000000001 RSI: dffffc0000000000 RDI: ffffffffb5d1e140 > > RBP: ffff88003b2df560 R08: dffffc0000000000 R09: 0000000000000000 > > R10: ffff88003b2df718 R11: 0000000000000000 R12: ffff88003b2df5d8 > > R13: 0000000000000064 R14: ffffffffb5d1e140 R15: 0000000000000000 > > vsnprintf+0x173/0x1700 lib/vsprintf.c:2136 > > We took a page fault in vsnprintf() while doing link_path_walk(), > which looks to be within an RCU read-side critical section. > > Maybe the page fault confused lockdep? > > Sigh. It is going to be a real pain if all printk()s need to be > outside of RCU read-side critical sections due to the possibility of > page faults...
printk() _should_ not fault AFAIK. If it does, you've done something dodgy.
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