Fix blockable memory allocation under rcu_read_lock in psi monitors
psi_fop_poll calls poll_wait which makes a blockable allocation. This
generates the following warning:
[ 22.339969] c0 898 BUG: sleeping function called from invalid context at mm/slab.h:393
[ 22.339972] c0 898 in_atomic(): 0, irqs_disabled(): 0, pid: 898, name: lmkd
[ 22.339979] c0 898 ------------[ cut here ]------------
[ 22.339981] c0 898 kernel BUG at kernel/sched/core.c:8448!
[ 22.339986] c0 898 ------------[ cut here ]------------
[ 22.339987] c0 898 kernel BUG at kernel/sched/core.c:8448!
[ 22.339989] c0 898 Internal error: Oops - BUG: 0 [#1] PREEMPT SMP
[ 22.339996] c0 898 Modules linked in:
[ 22.340001] c0 898 CPU: 0 PID: 898 Comm: lmkd Not tainted 4.9.153-gae6c134c27aa-dirty_audio-g3dce958 #1
[ 22.340002] c0 898 Hardware name: <redacted>
[ 22.340004] c0 898 task: fffffff3a6696000 task.stack: fffffff3977b4000
[ 22.340016] c0 898 PC is at ___might_sleep+0x104/0x10c
[ 22.340019] c0 898 LR is at ___might_sleep+0xdc/0x10c
...
[ 22.340201] c0 898 [<ffffff9f4bceaf2c>] ___might_sleep+0x104/0x10c
[ 22.340203] c0 898 [<ffffff9f4bceae14>] __might_sleep+0x24/0x38
[ 22.340209] c0 898 [<ffffff9f4be26d1c>] kmem_cache_alloc+0x60/0x338
[ 22.340213] c0 898 [<ffffff9f4be9684c>] ep_ptable_queue_proc+0x38/0xc8
[ 22.340219] c0 898 [<ffffff9f4bd18218>] psi_fop_poll+0x7c/0xbc
Fix this by using refcount during poll_wait and trigger destruction. This prevents trigger
from being destroyed during poll_wait call.
Bug: 124796537
Change-Id: Ib7feb96990f1cd96f1ab0e0720010ffa442c25d9
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
4 files changed
