60 lines
2.4 KiB
Diff
60 lines
2.4 KiB
Diff
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From 9a1a63848887fd99e6be49a3925d65751e424c8a Mon Sep 17 00:00:00 2001
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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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Date: Wed, 19 Feb 2014 11:56:06 +0100
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Subject: [PATCH] kernel/hrtimer: be non-freezeable in cpu_chill()
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Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.0/patches-4.0.4-rt1.tar.xz
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Since we replaced msleep() by hrtimer I see now and then (rarely) this:
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| [....] Waiting for /dev to be fully populated...
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| =====================================
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| [ BUG: udevd/229 still has locks held! ]
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| 3.12.11-rt17 #23 Not tainted
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| -------------------------------------
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| 1 lock held by udevd/229:
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| #0: (&type->i_mutex_dir_key#2){+.+.+.}, at: lookup_slow+0x28/0x98
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| stack backtrace:
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| CPU: 0 PID: 229 Comm: udevd Not tainted 3.12.11-rt17 #23
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| (unwind_backtrace+0x0/0xf8) from (show_stack+0x10/0x14)
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| (show_stack+0x10/0x14) from (dump_stack+0x74/0xbc)
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| (dump_stack+0x74/0xbc) from (do_nanosleep+0x120/0x160)
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| (do_nanosleep+0x120/0x160) from (hrtimer_nanosleep+0x90/0x110)
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| (hrtimer_nanosleep+0x90/0x110) from (cpu_chill+0x30/0x38)
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| (cpu_chill+0x30/0x38) from (dentry_kill+0x158/0x1ec)
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| (dentry_kill+0x158/0x1ec) from (dput+0x74/0x15c)
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| (dput+0x74/0x15c) from (lookup_real+0x4c/0x50)
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| (lookup_real+0x4c/0x50) from (__lookup_hash+0x34/0x44)
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| (__lookup_hash+0x34/0x44) from (lookup_slow+0x38/0x98)
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| (lookup_slow+0x38/0x98) from (path_lookupat+0x208/0x7fc)
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| (path_lookupat+0x208/0x7fc) from (filename_lookup+0x20/0x60)
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| (filename_lookup+0x20/0x60) from (user_path_at_empty+0x50/0x7c)
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| (user_path_at_empty+0x50/0x7c) from (user_path_at+0x14/0x1c)
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| (user_path_at+0x14/0x1c) from (vfs_fstatat+0x48/0x94)
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| (vfs_fstatat+0x48/0x94) from (SyS_stat64+0x14/0x30)
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| (SyS_stat64+0x14/0x30) from (ret_fast_syscall+0x0/0x48)
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For now I see no better way but to disable the freezer the sleep the period.
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Cc: stable-rt@vger.kernel.org
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Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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---
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kernel/time/hrtimer.c | 4 ++++
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1 file changed, 4 insertions(+)
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--- a/kernel/time/hrtimer.c
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+++ b/kernel/time/hrtimer.c
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@@ -1874,8 +1874,12 @@ void cpu_chill(void)
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struct timespec tu = {
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.tv_nsec = NSEC_PER_MSEC,
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};
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+ unsigned int freeze_flag = current->flags & PF_NOFREEZE;
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+ current->flags |= PF_NOFREEZE;
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hrtimer_nanosleep(&tu, NULL, HRTIMER_MODE_REL, CLOCK_MONOTONIC);
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+ if (!freeze_flag)
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+ current->flags &= ~PF_NOFREEZE;
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}
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EXPORT_SYMBOL(cpu_chill);
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#endif
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