From 37fc3173215bf467bb50351f5aa659c730e2b10e Mon Sep 17 00:00:00 2001 From: Sebastian Andrzej Siewior Date: Wed, 19 Feb 2014 11:56:06 +0100 Subject: kernel/hrtimer: be non-freezeable in cpu_chill() Since we replaced msleep() by hrtimer I see now and then (rarely) this: | [....] Waiting for /dev to be fully populated... | ===================================== | [ BUG: udevd/229 still has locks held! ] | 3.12.11-rt17 #23 Not tainted | ------------------------------------- | 1 lock held by udevd/229: | #0: (&type->i_mutex_dir_key#2){+.+.+.}, at: lookup_slow+0x28/0x98 | | stack backtrace: | CPU: 0 PID: 229 Comm: udevd Not tainted 3.12.11-rt17 #23 | (unwind_backtrace+0x0/0xf8) from (show_stack+0x10/0x14) | (show_stack+0x10/0x14) from (dump_stack+0x74/0xbc) | (dump_stack+0x74/0xbc) from (do_nanosleep+0x120/0x160) | (do_nanosleep+0x120/0x160) from (hrtimer_nanosleep+0x90/0x110) | (hrtimer_nanosleep+0x90/0x110) from (cpu_chill+0x30/0x38) | (cpu_chill+0x30/0x38) from (dentry_kill+0x158/0x1ec) | (dentry_kill+0x158/0x1ec) from (dput+0x74/0x15c) | (dput+0x74/0x15c) from (lookup_real+0x4c/0x50) | (lookup_real+0x4c/0x50) from (__lookup_hash+0x34/0x44) | (__lookup_hash+0x34/0x44) from (lookup_slow+0x38/0x98) | (lookup_slow+0x38/0x98) from (path_lookupat+0x208/0x7fc) | (path_lookupat+0x208/0x7fc) from (filename_lookup+0x20/0x60) | (filename_lookup+0x20/0x60) from (user_path_at_empty+0x50/0x7c) | (user_path_at_empty+0x50/0x7c) from (user_path_at+0x14/0x1c) | (user_path_at+0x14/0x1c) from (vfs_fstatat+0x48/0x94) | (vfs_fstatat+0x48/0x94) from (SyS_stat64+0x14/0x30) | (SyS_stat64+0x14/0x30) from (ret_fast_syscall+0x0/0x48) For now I see no better way but to disable the freezer the sleep the period. Cc: stable-rt@vger.kernel.org Signed-off-by: Sebastian Andrzej Siewior diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c index 5c26d2c..083815d 100644 --- a/kernel/hrtimer.c +++ b/kernel/hrtimer.c @@ -1899,8 +1899,12 @@ void cpu_chill(void) struct timespec tu = { .tv_nsec = NSEC_PER_MSEC, }; + unsigned int freeze_flag = current->flags & PF_NOFREEZE; + current->flags |= PF_NOFREEZE; hrtimer_nanosleep(&tu, NULL, HRTIMER_MODE_REL, CLOCK_MONOTONIC); + if (!freeze_flag) + current->flags &= ~PF_NOFREEZE; } EXPORT_SYMBOL(cpu_chill); #endif -- cgit v0.10.2