On Sun, Jun 14, 2015 at 06:06:21PM -0500, Larry Finger wrote:
> When booting kernels from Linux-next, the following is output:
>
> [ 2.816564] ===============================
> [ 2.816986] [ INFO: suspicious RCU usage. ]
> [ 2.817402] 4.1.0-rc7-next-20150612 #1 Not tainted
> [ 2.817881] -------------------------------
> [ 2.818297] kernel/sched/core.c:7318 Illegal context switch in
> RCU-bh read-side critical section!
> [ 2.819180]
> other info that might help us debug this:
>
> [ 2.819947]
> rcu_scheduler_active = 1, debug_locks = 0
> [ 2.820578] 3 locks held by systemd/1:
> [ 2.820954] #0: (rtnl_mutex){+.+.+.}, at: [<ffffffff815f0c8f>]
> rtnetlink_rcv+0x1f/0x40
> [ 2.821855] #1: (rcu_read_lock_bh){......}, at:
> [<ffffffff816a34e2>] ipv6_add_addr+0x62/0x540
> [ 2.822808] #2: (addrconf_hash_lock){+...+.}, at:
> [<ffffffff816a3604>] ipv6_add_addr+0x184/0x540
> [ 2.823790]
> stack backtrace:
> [ 2.824212] CPU: 0 PID: 1 Comm: systemd Not tainted
> 4.1.0-rc7-next-20150612 #1
> [ 2.824932] Hardware name: TOSHIBA TECRA A50-A/TECRA A50-A, BIOS
> Version 4.20 04/17/2014
> [ 2.825751] 0000000000000001 ffff880224e07838 ffffffff817263a4
> ffffffff810ccf2a
> [ 2.826560] ffff880224e08000 ffff880224e07868 ffffffff810b6827
> 0000000000000000
> [ 2.827368] ffffffff81a445d3 00000000000004f4 ffff88022682e100
> ffff880224e07898
> [ 2.828177] Call Trace:
> [ 2.828422] [<ffffffff817263a4>] dump_stack+0x4c/0x6e
> [ 2.828937] [<ffffffff810ccf2a>] ? console_unlock+0x1ca/0x510
> [ 2.829514] [<ffffffff810b6827>] lockdep_rcu_suspicious+0xe7/0x120
> [ 2.830139] [<ffffffff8108cf05>] ___might_sleep+0x1d5/0x1f0
> [ 2.830699] [<ffffffff8108cf6d>] __might_sleep+0x4d/0x90
> [ 2.831239] [<ffffffff811f3789>] ? create_object+0x39/0x2e0
> [ 2.831800] [<ffffffff811da427>] kmem_cache_alloc+0x47/0x250
> [ 2.832375] [<ffffffff813c19ae>] ? find_next_zero_bit+0x1e/0x20
> [ 2.832973] [<ffffffff811f3789>] create_object+0x39/0x2e0
> [ 2.833515] [<ffffffff810b7eb6>] ? mark_held_locks+0x66/0x90
> [ 2.834089] [<ffffffff8172efab>] ? _raw_spin_unlock_irqrestore+0x4b/0x60
> [ 2.834761] [<ffffffff817193c1>] kmemleak_alloc_percpu+0x61/0xe0
It seems to be a problem specific to kmemleak_alloc_percpu()
which does not get the 'gfp' param from pcpu_alloc. The comment from
kmemleak_alloc_percpu():
/*
* This function is called from the kernel percpu allocator when a new object
* (memory block) is allocated (alloc_percpu). It assumes GFP_KERNEL
* allocation.
*/
I will try out a change tomorrow.
--Martin
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