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author | Luis Claudio R. Goncalves <lclaudio@uudg.org> | 2019-06-25 11:28:04 -0300 |
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committer | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2019-07-23 14:57:14 -0400 |
commit | 80f3230e0d571c7450ab13b885c8e4273ddb1d86 (patch) | |
tree | 52622f4693f04a22af16e63ce0d71ea8c666f270 /Documentation/networking/ip-sysctl.txt | |
parent | ae2024ba663c9e68716be9c53d22314f55342f08 (diff) |
mm/zswap: Do not disable preemption in zswap_frontswap_store()
[ Upstream commit 4e4cf4be79635e67144632d9135286381acbc95a ]
Zswap causes "BUG: scheduling while atomic" by blocking on a rt_spin_lock() with
preemption disabled. The preemption is disabled by get_cpu_var() in
zswap_frontswap_store() to protect the access of the zswap_dstmem percpu variable.
Use get_locked_var() to protect the percpu zswap_dstmem variable, making the
code preemptive.
As get_cpu_ptr() also disables preemption, replace it by this_cpu_ptr() and
remove the counterpart put_cpu_ptr().
Steps to Reproduce:
1. # grubby --args "zswap.enabled=1" --update-kernel DEFAULT
2. # reboot
3. Calculate the amount o memory to be used by the test:
---> grep MemAvailable /proc/meminfo
---> Add 25% ~ 50% to that value
4. # stress --vm 1 --vm-bytes ${MemAvailable+25%} --timeout 240s
Usually, in less than 5 minutes the backtrace listed below appears, followed
by a kernel panic:
| BUG: scheduling while atomic: kswapd1/181/0x00000002
|
| Preemption disabled at:
| [<ffffffff8b2a6cda>] zswap_frontswap_store+0x21a/0x6e1
|
| Kernel panic - not syncing: scheduling while atomic
| CPU: 14 PID: 181 Comm: kswapd1 Kdump: loaded Not tainted 5.0.14-rt9 #1
| Hardware name: AMD Pence/Pence, BIOS WPN2321X_Weekly_12_03_21 03/19/2012
| Call Trace:
| panic+0x106/0x2a7
| __schedule_bug.cold+0x3f/0x51
| __schedule+0x5cb/0x6f0
| schedule+0x43/0xd0
| rt_spin_lock_slowlock_locked+0x114/0x2b0
| rt_spin_lock_slowlock+0x51/0x80
| zbud_alloc+0x1da/0x2d0
| zswap_frontswap_store+0x31a/0x6e1
| __frontswap_store+0xab/0x130
| swap_writepage+0x39/0x70
| pageout.isra.0+0xe3/0x320
| shrink_page_list+0xa8e/0xd10
| shrink_inactive_list+0x251/0x840
| shrink_node_memcg+0x213/0x770
| shrink_node+0xd9/0x450
| balance_pgdat+0x2d5/0x510
| kswapd+0x218/0x470
| kthread+0xfb/0x130
| ret_from_fork+0x27/0x50
Cc: stable-rt@vger.kernel.org
Reported-by: Ping Fang <pifang@redhat.com>
Signed-off-by: Luis Claudio R. Goncalves <lgoncalv@redhat.com>
Reviewed-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Diffstat (limited to 'Documentation/networking/ip-sysctl.txt')
0 files changed, 0 insertions, 0 deletions