| 
									
										
										
										
											2006-09-30 23:28:55 -07:00
										 |  |  | /*
 | 
					
						
							|  |  |  |  * tsacct.c - System accounting over taskstats interface | 
					
						
							|  |  |  |  * | 
					
						
							|  |  |  |  * Copyright (C) Jay Lan,	<jlan@sgi.com> | 
					
						
							|  |  |  |  * | 
					
						
							|  |  |  |  * | 
					
						
							|  |  |  |  * This program is free software; you can redistribute it and/or modify | 
					
						
							|  |  |  |  * it under the terms of the GNU General Public License as published by | 
					
						
							|  |  |  |  * the Free Software Foundation; either version 2 of the License, or | 
					
						
							|  |  |  |  * (at your option) any later version. | 
					
						
							|  |  |  |  * | 
					
						
							|  |  |  |  * This program is distributed in the hope that it will be useful, | 
					
						
							|  |  |  |  * but WITHOUT ANY WARRANTY; without even the implied warranty of | 
					
						
							|  |  |  |  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the | 
					
						
							|  |  |  |  * GNU General Public License for more details. | 
					
						
							|  |  |  |  * | 
					
						
							|  |  |  |  */ | 
					
						
							|  |  |  | 
 | 
					
						
							|  |  |  | #include <linux/kernel.h>
 | 
					
						
							|  |  |  | #include <linux/sched.h>
 | 
					
						
							|  |  |  | #include <linux/tsacct_kern.h>
 | 
					
						
							|  |  |  | #include <linux/acct.h>
 | 
					
						
							| 
									
										
										
										
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										 |  |  | #include <linux/jiffies.h>
 | 
					
						
							| 
									
										
										
										
											2010-03-05 13:41:39 -08:00
										 |  |  | #include <linux/mm.h>
 | 
					
						
							| 
									
										
										
										
											2006-09-30 23:28:55 -07:00
										 |  |  | 
 | 
					
						
							|  |  |  | /*
 | 
					
						
							|  |  |  |  * fill in basic accounting fields | 
					
						
							|  |  |  |  */ | 
					
						
							| 
									
										
										
										
											2012-02-07 17:56:49 -08:00
										 |  |  | void bacct_add_tsk(struct user_namespace *user_ns, | 
					
						
							|  |  |  | 		   struct pid_namespace *pid_ns, | 
					
						
							|  |  |  | 		   struct taskstats *stats, struct task_struct *tsk) | 
					
						
							| 
									
										
										
										
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										 |  |  | { | 
					
						
							| 
									
										
										
										
											2008-11-14 10:39:19 +11:00
										 |  |  | 	const struct cred *tcred; | 
					
						
							| 
									
										
										
										
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										 |  |  | 	struct timespec uptime, ts; | 
					
						
							| 
									
										
										
										
											2012-11-13 14:20:55 +01:00
										 |  |  | 	cputime_t utime, stime, utimescaled, stimescaled; | 
					
						
							| 
									
										
										
										
											2008-07-25 01:48:50 -07:00
										 |  |  | 	u64 ac_etime; | 
					
						
							| 
									
										
										
										
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										 |  |  | 
 | 
					
						
							|  |  |  | 	BUILD_BUG_ON(TS_COMM_LEN < TASK_COMM_LEN); | 
					
						
							|  |  |  | 
 | 
					
						
							|  |  |  | 	/* calculate task elapsed time in timespec */ | 
					
						
							|  |  |  | 	do_posix_clock_monotonic_gettime(&uptime); | 
					
						
							| 
									
										
										
										
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										 |  |  | 	ts = timespec_sub(uptime, tsk->start_time); | 
					
						
							| 
									
										
										
										
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										 |  |  | 	/* rebase elapsed time to usec (should never be negative) */ | 
					
						
							| 
									
										
										
										
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										 |  |  | 	ac_etime = timespec_to_ns(&ts); | 
					
						
							|  |  |  | 	do_div(ac_etime, NSEC_PER_USEC); | 
					
						
							|  |  |  | 	stats->ac_etime = ac_etime; | 
					
						
							| 
									
										
										
										
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										 |  |  | 	stats->ac_btime = get_seconds() - ts.tv_sec; | 
					
						
							| 
									
										
										
										
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										 |  |  | 	if (thread_group_leader(tsk)) { | 
					
						
							|  |  |  | 		stats->ac_exitcode = tsk->exit_code; | 
					
						
							|  |  |  | 		if (tsk->flags & PF_FORKNOEXEC) | 
					
						
							|  |  |  | 			stats->ac_flag |= AFORK; | 
					
						
							|  |  |  | 	} | 
					
						
							|  |  |  | 	if (tsk->flags & PF_SUPERPRIV) | 
					
						
							|  |  |  | 		stats->ac_flag |= ASU; | 
					
						
							|  |  |  | 	if (tsk->flags & PF_DUMPCORE) | 
					
						
							|  |  |  | 		stats->ac_flag |= ACORE; | 
					
						
							|  |  |  | 	if (tsk->flags & PF_SIGNALED) | 
					
						
							|  |  |  | 		stats->ac_flag |= AXSIG; | 
					
						
							|  |  |  | 	stats->ac_nice	 = task_nice(tsk); | 
					
						
							|  |  |  | 	stats->ac_sched	 = tsk->policy; | 
					
						
							| 
									
										
										
										
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										 |  |  | 	stats->ac_pid	 = task_pid_nr_ns(tsk, pid_ns); | 
					
						
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										 |  |  | 	rcu_read_lock(); | 
					
						
							| 
									
										
										
										
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										 |  |  | 	tcred = __task_cred(tsk); | 
					
						
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										 |  |  | 	stats->ac_uid	 = from_kuid_munged(user_ns, tcred->uid); | 
					
						
							|  |  |  | 	stats->ac_gid	 = from_kgid_munged(user_ns, tcred->gid); | 
					
						
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										 |  |  | 	stats->ac_ppid	 = pid_alive(tsk) ? | 
					
						
							| 
									
										
										
										
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										 |  |  | 		task_tgid_nr_ns(rcu_dereference(tsk->real_parent), pid_ns) : 0; | 
					
						
							| 
									
										
										
										
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										 |  |  | 	rcu_read_unlock(); | 
					
						
							| 
									
										
										
										
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										 |  |  | 
 | 
					
						
							|  |  |  | 	task_cputime(tsk, &utime, &stime); | 
					
						
							|  |  |  | 	stats->ac_utime = cputime_to_usecs(utime); | 
					
						
							|  |  |  | 	stats->ac_stime = cputime_to_usecs(stime); | 
					
						
							|  |  |  | 
 | 
					
						
							|  |  |  | 	task_cputime_scaled(tsk, &utimescaled, &stimescaled); | 
					
						
							|  |  |  | 	stats->ac_utimescaled = cputime_to_usecs(utimescaled); | 
					
						
							|  |  |  | 	stats->ac_stimescaled = cputime_to_usecs(stimescaled); | 
					
						
							|  |  |  | 
 | 
					
						
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										 |  |  | 	stats->ac_minflt = tsk->min_flt; | 
					
						
							|  |  |  | 	stats->ac_majflt = tsk->maj_flt; | 
					
						
							|  |  |  | 
 | 
					
						
							|  |  |  | 	strncpy(stats->ac_comm, tsk->comm, sizeof(stats->ac_comm)); | 
					
						
							|  |  |  | } | 
					
						
							|  |  |  | 
 | 
					
						
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											2006-09-30 23:28:58 -07:00
										 |  |  | 
 | 
					
						
							|  |  |  | #ifdef CONFIG_TASK_XACCT
 | 
					
						
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										 |  |  | 
 | 
					
						
							|  |  |  | #define KB 1024
 | 
					
						
							|  |  |  | #define MB (1024*KB)
 | 
					
						
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										 |  |  | #define KB_MASK (~(KB-1))
 | 
					
						
							| 
									
										
										
										
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										 |  |  | /*
 | 
					
						
							|  |  |  |  * fill in extended accounting fields | 
					
						
							|  |  |  |  */ | 
					
						
							|  |  |  | void xacct_add_tsk(struct taskstats *stats, struct task_struct *p) | 
					
						
							|  |  |  | { | 
					
						
							| 
									
										
										
										
											2006-10-29 22:46:43 -08:00
										 |  |  | 	struct mm_struct *mm; | 
					
						
							|  |  |  | 
 | 
					
						
							| 
									
										
										
										
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										 |  |  | 	/* convert pages-usec to Mbyte-usec */ | 
					
						
							|  |  |  | 	stats->coremem = p->acct_rss_mem1 * PAGE_SIZE / MB; | 
					
						
							|  |  |  | 	stats->virtmem = p->acct_vm_mem1 * PAGE_SIZE / MB; | 
					
						
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										 |  |  | 	mm = get_task_mm(p); | 
					
						
							|  |  |  | 	if (mm) { | 
					
						
							| 
									
										
										
										
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										 |  |  | 		/* adjust to KB unit */ | 
					
						
							| 
									
										
										
										
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										 |  |  | 		stats->hiwater_rss   = get_mm_hiwater_rss(mm) * PAGE_SIZE / KB; | 
					
						
							|  |  |  | 		stats->hiwater_vm    = get_mm_hiwater_vm(mm)  * PAGE_SIZE / KB; | 
					
						
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										 |  |  | 		mmput(mm); | 
					
						
							| 
									
										
										
										
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										 |  |  | 	} | 
					
						
							| 
									
										
										
										
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										 |  |  | 	stats->read_char	= p->ioac.rchar & KB_MASK; | 
					
						
							|  |  |  | 	stats->write_char	= p->ioac.wchar & KB_MASK; | 
					
						
							|  |  |  | 	stats->read_syscalls	= p->ioac.syscr & KB_MASK; | 
					
						
							|  |  |  | 	stats->write_syscalls	= p->ioac.syscw & KB_MASK; | 
					
						
							| 
									
										
										
										
											2006-12-10 02:19:53 -08:00
										 |  |  | #ifdef CONFIG_TASK_IO_ACCOUNTING
 | 
					
						
							| 
									
										
										
										
											2011-09-19 17:10:57 -07:00
										 |  |  | 	stats->read_bytes	= p->ioac.read_bytes & KB_MASK; | 
					
						
							|  |  |  | 	stats->write_bytes	= p->ioac.write_bytes & KB_MASK; | 
					
						
							|  |  |  | 	stats->cancelled_write_bytes = p->ioac.cancelled_write_bytes & KB_MASK; | 
					
						
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											2006-12-10 02:19:53 -08:00
										 |  |  | #else
 | 
					
						
							|  |  |  | 	stats->read_bytes	= 0; | 
					
						
							|  |  |  | 	stats->write_bytes	= 0; | 
					
						
							|  |  |  | 	stats->cancelled_write_bytes = 0; | 
					
						
							|  |  |  | #endif
 | 
					
						
							| 
									
										
										
										
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										 |  |  | } | 
					
						
							| 
									
										
										
										
											2006-09-30 23:29:00 -07:00
										 |  |  | #undef KB
 | 
					
						
							|  |  |  | #undef MB
 | 
					
						
							| 
									
										
										
										
											2006-09-30 23:28:59 -07:00
										 |  |  | 
 | 
					
						
							| 
									
										
										
										
											2012-11-13 14:20:55 +01:00
										 |  |  | static void __acct_update_integrals(struct task_struct *tsk, | 
					
						
							|  |  |  | 				    cputime_t utime, cputime_t stime) | 
					
						
							| 
									
										
										
										
											2006-09-30 23:28:59 -07:00
										 |  |  | { | 
					
						
							|  |  |  | 	if (likely(tsk->mm)) { | 
					
						
							| 
									
										
										
										
											2008-07-25 01:48:40 -07:00
										 |  |  | 		cputime_t time, dtime; | 
					
						
							|  |  |  | 		struct timeval value; | 
					
						
							| 
									
										
											  
											
												Fix fixpoint divide exception in acct_update_integrals
Frans Pop reported the crash below when running an s390 kernel under Hercules:
  Kernel BUG at 000738b4  verbose debug info unavailable!
  fixpoint divide exception: 0009  #1! SMP
  Modules linked in: nfs lockd nfs_acl sunrpc ctcm fsm tape_34xx
     cu3088 tape ccwgroup tape_class ext3 jbd mbcache dm_mirror dm_log dm_snapshot
     dm_mod dasd_eckd_mod dasd_mod
  CPU: 0 Not tainted 2.6.27.19 #13
  Process awk (pid: 2069, task: 0f9ed9b8, ksp: 0f4f7d18)
  Krnl PSW : 070c1000 800738b4 (acct_update_integrals+0x4c/0x118)
             R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:0 CC:1 PM:0
  Krnl GPRS: 00000000 000007d0 7fffffff fffff830
             00000000 ffffffff 00000002 0f9ed9b8
             00000000 00008ca0 00000000 0f9ed9b8
             0f9edda4 8007386e 0f4f7ec8 0f4f7e98
  Krnl Code: 800738aa: a71807d0         lhi     %r1,2000
             800738ae: 8c200001         srdl    %r2,1
             800738b2: 1d21             dr      %r2,%r1
            >800738b4: 5810d10e         l       %r1,270(%r13)
             800738b8: 1823             lr      %r2,%r3
             800738ba: 4130f060         la      %r3,96(%r15)
             800738be: 0de1             basr    %r14,%r1
             800738c0: 5800f060         l       %r0,96(%r15)
  Call Trace:
  ( <000000000004fdea>! blocking_notifier_call_chain+0x1e/0x2c)
    <0000000000038502>! do_exit+0x106/0x7c0
    <0000000000038c36>! do_group_exit+0x7a/0xb4
    <0000000000038c8e>! SyS_exit_group+0x1e/0x30
    <0000000000021c28>! sysc_do_restart+0x12/0x16
    <0000000077e7e924>! 0x77e7e924
Reason for this is that cpu time accounting usually only happens from
interrupt context, but acct_update_integrals gets also called from
process context with interrupts enabled.
So in acct_update_integrals we may end up with the following scenario:
Between reading tsk->stime/tsk->utime and tsk->acct_timexpd an interrupt
happens which updates accouting values.  This causes acct_timexpd to be
greater than the former stime + utime.  The subsequent calculation of
	dtime = cputime_sub(time, tsk->acct_timexpd);
will be negative and the division performed by
	cputime_to_jiffies(dtime)
will generate an exception since the result won't fit into a 32 bit
register.
In order to fix this just always disable interrupts while accessing any
of the accounting values.
Reported by: Frans Pop <elendil@planet.nl>
Tested by: Frans Pop <elendil@planet.nl>
Cc: stable@kernel.org
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
											
										 
											2009-03-09 13:31:59 +01:00
										 |  |  | 		unsigned long flags; | 
					
						
							| 
									
										
										
										
											2008-07-25 01:48:40 -07:00
										 |  |  | 		u64 delta; | 
					
						
							|  |  |  | 
 | 
					
						
							| 
									
										
											  
											
												Fix fixpoint divide exception in acct_update_integrals
Frans Pop reported the crash below when running an s390 kernel under Hercules:
  Kernel BUG at 000738b4  verbose debug info unavailable!
  fixpoint divide exception: 0009  #1! SMP
  Modules linked in: nfs lockd nfs_acl sunrpc ctcm fsm tape_34xx
     cu3088 tape ccwgroup tape_class ext3 jbd mbcache dm_mirror dm_log dm_snapshot
     dm_mod dasd_eckd_mod dasd_mod
  CPU: 0 Not tainted 2.6.27.19 #13
  Process awk (pid: 2069, task: 0f9ed9b8, ksp: 0f4f7d18)
  Krnl PSW : 070c1000 800738b4 (acct_update_integrals+0x4c/0x118)
             R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:0 CC:1 PM:0
  Krnl GPRS: 00000000 000007d0 7fffffff fffff830
             00000000 ffffffff 00000002 0f9ed9b8
             00000000 00008ca0 00000000 0f9ed9b8
             0f9edda4 8007386e 0f4f7ec8 0f4f7e98
  Krnl Code: 800738aa: a71807d0         lhi     %r1,2000
             800738ae: 8c200001         srdl    %r2,1
             800738b2: 1d21             dr      %r2,%r1
            >800738b4: 5810d10e         l       %r1,270(%r13)
             800738b8: 1823             lr      %r2,%r3
             800738ba: 4130f060         la      %r3,96(%r15)
             800738be: 0de1             basr    %r14,%r1
             800738c0: 5800f060         l       %r0,96(%r15)
  Call Trace:
  ( <000000000004fdea>! blocking_notifier_call_chain+0x1e/0x2c)
    <0000000000038502>! do_exit+0x106/0x7c0
    <0000000000038c36>! do_group_exit+0x7a/0xb4
    <0000000000038c8e>! SyS_exit_group+0x1e/0x30
    <0000000000021c28>! sysc_do_restart+0x12/0x16
    <0000000077e7e924>! 0x77e7e924
Reason for this is that cpu time accounting usually only happens from
interrupt context, but acct_update_integrals gets also called from
process context with interrupts enabled.
So in acct_update_integrals we may end up with the following scenario:
Between reading tsk->stime/tsk->utime and tsk->acct_timexpd an interrupt
happens which updates accouting values.  This causes acct_timexpd to be
greater than the former stime + utime.  The subsequent calculation of
	dtime = cputime_sub(time, tsk->acct_timexpd);
will be negative and the division performed by
	cputime_to_jiffies(dtime)
will generate an exception since the result won't fit into a 32 bit
register.
In order to fix this just always disable interrupts while accessing any
of the accounting values.
Reported by: Frans Pop <elendil@planet.nl>
Tested by: Frans Pop <elendil@planet.nl>
Cc: stable@kernel.org
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
											
										 
											2009-03-09 13:31:59 +01:00
										 |  |  | 		local_irq_save(flags); | 
					
						
							| 
									
										
										
										
											2012-11-13 14:20:55 +01:00
										 |  |  | 		time = stime + utime; | 
					
						
							| 
									
										
										
										
											2011-12-15 14:56:09 +01:00
										 |  |  | 		dtime = time - tsk->acct_timexpd; | 
					
						
							| 
									
										
										
										
											2008-07-25 01:48:40 -07:00
										 |  |  | 		jiffies_to_timeval(cputime_to_jiffies(dtime), &value); | 
					
						
							|  |  |  | 		delta = value.tv_sec; | 
					
						
							|  |  |  | 		delta = delta * USEC_PER_SEC + value.tv_usec; | 
					
						
							| 
									
										
										
										
											2006-09-30 23:28:59 -07:00
										 |  |  | 
 | 
					
						
							|  |  |  | 		if (delta == 0) | 
					
						
							| 
									
										
											  
											
												Fix fixpoint divide exception in acct_update_integrals
Frans Pop reported the crash below when running an s390 kernel under Hercules:
  Kernel BUG at 000738b4  verbose debug info unavailable!
  fixpoint divide exception: 0009  #1! SMP
  Modules linked in: nfs lockd nfs_acl sunrpc ctcm fsm tape_34xx
     cu3088 tape ccwgroup tape_class ext3 jbd mbcache dm_mirror dm_log dm_snapshot
     dm_mod dasd_eckd_mod dasd_mod
  CPU: 0 Not tainted 2.6.27.19 #13
  Process awk (pid: 2069, task: 0f9ed9b8, ksp: 0f4f7d18)
  Krnl PSW : 070c1000 800738b4 (acct_update_integrals+0x4c/0x118)
             R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:0 CC:1 PM:0
  Krnl GPRS: 00000000 000007d0 7fffffff fffff830
             00000000 ffffffff 00000002 0f9ed9b8
             00000000 00008ca0 00000000 0f9ed9b8
             0f9edda4 8007386e 0f4f7ec8 0f4f7e98
  Krnl Code: 800738aa: a71807d0         lhi     %r1,2000
             800738ae: 8c200001         srdl    %r2,1
             800738b2: 1d21             dr      %r2,%r1
            >800738b4: 5810d10e         l       %r1,270(%r13)
             800738b8: 1823             lr      %r2,%r3
             800738ba: 4130f060         la      %r3,96(%r15)
             800738be: 0de1             basr    %r14,%r1
             800738c0: 5800f060         l       %r0,96(%r15)
  Call Trace:
  ( <000000000004fdea>! blocking_notifier_call_chain+0x1e/0x2c)
    <0000000000038502>! do_exit+0x106/0x7c0
    <0000000000038c36>! do_group_exit+0x7a/0xb4
    <0000000000038c8e>! SyS_exit_group+0x1e/0x30
    <0000000000021c28>! sysc_do_restart+0x12/0x16
    <0000000077e7e924>! 0x77e7e924
Reason for this is that cpu time accounting usually only happens from
interrupt context, but acct_update_integrals gets also called from
process context with interrupts enabled.
So in acct_update_integrals we may end up with the following scenario:
Between reading tsk->stime/tsk->utime and tsk->acct_timexpd an interrupt
happens which updates accouting values.  This causes acct_timexpd to be
greater than the former stime + utime.  The subsequent calculation of
	dtime = cputime_sub(time, tsk->acct_timexpd);
will be negative and the division performed by
	cputime_to_jiffies(dtime)
will generate an exception since the result won't fit into a 32 bit
register.
In order to fix this just always disable interrupts while accessing any
of the accounting values.
Reported by: Frans Pop <elendil@planet.nl>
Tested by: Frans Pop <elendil@planet.nl>
Cc: stable@kernel.org
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
											
										 
											2009-03-09 13:31:59 +01:00
										 |  |  | 			goto out; | 
					
						
							| 
									
										
										
										
											2008-07-25 01:48:40 -07:00
										 |  |  | 		tsk->acct_timexpd = time; | 
					
						
							| 
									
										
										
										
											2006-09-30 23:28:59 -07:00
										 |  |  | 		tsk->acct_rss_mem1 += delta * get_mm_rss(tsk->mm); | 
					
						
							|  |  |  | 		tsk->acct_vm_mem1 += delta * tsk->mm->total_vm; | 
					
						
							| 
									
										
											  
											
												Fix fixpoint divide exception in acct_update_integrals
Frans Pop reported the crash below when running an s390 kernel under Hercules:
  Kernel BUG at 000738b4  verbose debug info unavailable!
  fixpoint divide exception: 0009  #1! SMP
  Modules linked in: nfs lockd nfs_acl sunrpc ctcm fsm tape_34xx
     cu3088 tape ccwgroup tape_class ext3 jbd mbcache dm_mirror dm_log dm_snapshot
     dm_mod dasd_eckd_mod dasd_mod
  CPU: 0 Not tainted 2.6.27.19 #13
  Process awk (pid: 2069, task: 0f9ed9b8, ksp: 0f4f7d18)
  Krnl PSW : 070c1000 800738b4 (acct_update_integrals+0x4c/0x118)
             R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:0 CC:1 PM:0
  Krnl GPRS: 00000000 000007d0 7fffffff fffff830
             00000000 ffffffff 00000002 0f9ed9b8
             00000000 00008ca0 00000000 0f9ed9b8
             0f9edda4 8007386e 0f4f7ec8 0f4f7e98
  Krnl Code: 800738aa: a71807d0         lhi     %r1,2000
             800738ae: 8c200001         srdl    %r2,1
             800738b2: 1d21             dr      %r2,%r1
            >800738b4: 5810d10e         l       %r1,270(%r13)
             800738b8: 1823             lr      %r2,%r3
             800738ba: 4130f060         la      %r3,96(%r15)
             800738be: 0de1             basr    %r14,%r1
             800738c0: 5800f060         l       %r0,96(%r15)
  Call Trace:
  ( <000000000004fdea>! blocking_notifier_call_chain+0x1e/0x2c)
    <0000000000038502>! do_exit+0x106/0x7c0
    <0000000000038c36>! do_group_exit+0x7a/0xb4
    <0000000000038c8e>! SyS_exit_group+0x1e/0x30
    <0000000000021c28>! sysc_do_restart+0x12/0x16
    <0000000077e7e924>! 0x77e7e924
Reason for this is that cpu time accounting usually only happens from
interrupt context, but acct_update_integrals gets also called from
process context with interrupts enabled.
So in acct_update_integrals we may end up with the following scenario:
Between reading tsk->stime/tsk->utime and tsk->acct_timexpd an interrupt
happens which updates accouting values.  This causes acct_timexpd to be
greater than the former stime + utime.  The subsequent calculation of
	dtime = cputime_sub(time, tsk->acct_timexpd);
will be negative and the division performed by
	cputime_to_jiffies(dtime)
will generate an exception since the result won't fit into a 32 bit
register.
In order to fix this just always disable interrupts while accessing any
of the accounting values.
Reported by: Frans Pop <elendil@planet.nl>
Tested by: Frans Pop <elendil@planet.nl>
Cc: stable@kernel.org
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
											
										 
											2009-03-09 13:31:59 +01:00
										 |  |  | 	out: | 
					
						
							|  |  |  | 		local_irq_restore(flags); | 
					
						
							| 
									
										
										
										
											2006-09-30 23:28:59 -07:00
										 |  |  | 	} | 
					
						
							|  |  |  | } | 
					
						
							|  |  |  | 
 | 
					
						
							| 
									
										
										
										
											2012-11-13 14:20:55 +01:00
										 |  |  | /**
 | 
					
						
							|  |  |  |  * acct_update_integrals - update mm integral fields in task_struct | 
					
						
							|  |  |  |  * @tsk: task_struct for accounting | 
					
						
							|  |  |  |  */ | 
					
						
							|  |  |  | void acct_update_integrals(struct task_struct *tsk) | 
					
						
							|  |  |  | { | 
					
						
							|  |  |  | 	cputime_t utime, stime; | 
					
						
							|  |  |  | 
 | 
					
						
							|  |  |  | 	task_cputime(tsk, &utime, &stime); | 
					
						
							|  |  |  | 	__acct_update_integrals(tsk, utime, stime); | 
					
						
							|  |  |  | } | 
					
						
							|  |  |  | 
 | 
					
						
							|  |  |  | /**
 | 
					
						
							|  |  |  |  * acct_account_cputime - update mm integral after cputime update | 
					
						
							|  |  |  |  * @tsk: task_struct for accounting | 
					
						
							|  |  |  |  */ | 
					
						
							|  |  |  | void acct_account_cputime(struct task_struct *tsk) | 
					
						
							|  |  |  | { | 
					
						
							|  |  |  | 	__acct_update_integrals(tsk, tsk->utime, tsk->stime); | 
					
						
							|  |  |  | } | 
					
						
							|  |  |  | 
 | 
					
						
							| 
									
										
										
										
											2006-09-30 23:28:59 -07:00
										 |  |  | /**
 | 
					
						
							|  |  |  |  * acct_clear_integrals - clear the mm integral fields in task_struct | 
					
						
							|  |  |  |  * @tsk: task_struct whose accounting fields are cleared | 
					
						
							|  |  |  |  */ | 
					
						
							|  |  |  | void acct_clear_integrals(struct task_struct *tsk) | 
					
						
							|  |  |  | { | 
					
						
							| 
									
										
										
										
											2008-07-25 01:48:40 -07:00
										 |  |  | 	tsk->acct_timexpd = 0; | 
					
						
							| 
									
										
										
										
											2006-09-30 23:28:59 -07:00
										 |  |  | 	tsk->acct_rss_mem1 = 0; | 
					
						
							|  |  |  | 	tsk->acct_vm_mem1 = 0; | 
					
						
							|  |  |  | } | 
					
						
							| 
									
										
										
										
											2006-09-30 23:28:58 -07:00
										 |  |  | #endif
 |