From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <42C0EBAB.8070709@sw.ru> Date: Tue, 28 Jun 2005 10:18:19 +0400 From: Kirill Korotaev MIME-Version: 1.0 Subject: Re: [RFC] Fix SMP brokenness for PF_FREEZE and make freezing usable for other purposes References: <20050625025122.GC22393@atrey.karlin.mff.cuni.cz> <20050626023053.GA2871@atrey.karlin.mff.cuni.cz> <20050626030925.GA4156@atrey.karlin.mff.cuni.cz> <20050627141320.GA4945@atrey.karlin.mff.cuni.cz> In-Reply-To: Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Christoph Lameter Cc: Pavel Machek , Linus Torvalds , linux-mm@kvack.org, linux-kernel@vger.kernel.org, raybry@engr.sgi.com, Alexey Kuznetsov List-ID: commented with <<<< inside >>Approach seems okay... Perhaps better place is something like >>kernel/freezer.c so it stays separate file? It is not really scheduler >>core, and it is only conditionally compiled... > > > There is already lots of other conditional code in kernel/sched.c and this > is just one function. It is scheduler like and uses scheduler variables > since it suspends a process. So lets move it there. > > I think this is as far as I can take it. Could you test this and see > if it works okay? > > For suspension for migration do: > > 1. down(&freezer_sem) > > 2. Signal processes to sleep (see kernel/power/process.c). Basically > set the TIF_FREEZE and may be do the fake signal thing. > > 3. If all processes have PF_FROZEN set then they are asleep. > > 4. Do migration things > > 5. complete_all(&thaw) > > 6. up(&freezer_sem) > > ---- > Revise handling of freezing in the suspend code > > The current suspend code modifies thread flags from outside the context of process. > This creates a SMP race. > > The patch fixes that by introducing a TIF_FREEZE flag (for all arches). Also > > - Uses a completion handler instead of waiting in a schedule loop in the refrigerator. > > - Introduces a semaphore freezer_sem to provide a way that multiple kernel > subsystems can use the freezing ability without interfering with one another. > > - Include necessary definitions for the migration code if CONFIG_MIGRATE is set. > > - Removes PF_FREEZE > > Signed-off-by: Christoph Lameter > > Index: linux-2.6.12/include/linux/sched.h > =================================================================== > --- linux-2.6.12.orig/include/linux/sched.h 2005-06-27 05:20:15.000000000 +0000 > +++ linux-2.6.12/include/linux/sched.h 2005-06-27 05:33:46.000000000 +0000 > @@ -804,7 +804,6 @@ do { if (atomic_dec_and_test(&(tsk)->usa > #define PF_MEMALLOC 0x00000800 /* Allocating memory */ > #define PF_FLUSHER 0x00001000 /* responsible for disk writeback */ > #define PF_USED_MATH 0x00002000 /* if unset the fpu must be initialized before use */ > -#define PF_FREEZE 0x00004000 /* this task is being frozen for suspend now */ > #define PF_NOFREEZE 0x00008000 /* this thread should not be frozen */ > #define PF_FROZEN 0x00010000 /* frozen for system suspend */ > #define PF_FSTRANS 0x00020000 /* inside a filesystem transaction */ > @@ -1265,78 +1264,37 @@ extern void normalize_rt_tasks(void); > > #endif > > -#ifdef CONFIG_PM > -/* > - * Check if a process has been frozen > - */ > -static inline int frozen(struct task_struct *p) > -{ > - return p->flags & PF_FROZEN; > -} > - > -/* > - * Check if there is a request to freeze a process > - */ > -static inline int freezing(struct task_struct *p) > -{ > - return p->flags & PF_FREEZE; > -} > +#if defined(CONFIG_PM) || defined(CONFIG_MIGRATE) <<<< why not to make a single option CONFIG_REFRIGERATOR? It looks to be a more robust way, since there are multiple users of it. > +extern struct semaphore freezer_sem; > +extern struct completion thaw; > > -/* > - * Request that a process be frozen > - * FIXME: SMP problem. We may not modify other process' flags! > - */ > -static inline void freeze(struct task_struct *p) > -{ > - p->flags |= PF_FREEZE; > -} > - > -/* > - * Wake up a frozen process > - */ > -static inline int thaw_process(struct task_struct *p) > -{ > - if (frozen(p)) { > - p->flags &= ~PF_FROZEN; > - wake_up_process(p); > - return 1; > - } > - return 0; > -} > +extern void refrigerator(void); > > -/* > - * freezing is complete, mark process as frozen > - */ > -static inline void frozen_process(struct task_struct *p) > +static inline int freezing(struct task_struct *p) > { > - p->flags = (p->flags & ~PF_FREEZE) | PF_FROZEN; > + return test_ti_thread_flag(p->thread_info, TIF_FREEZE); > } > > -extern void refrigerator(void); > -extern int freeze_processes(void); > -extern void thaw_processes(void); > - > static inline int try_to_freeze(void) > { > - if (freezing(current)) { > + if (test_thread_flag(TIF_FREEZE)) { > refrigerator(); > return 1; > } else > return 0; > } > #else > -static inline int frozen(struct task_struct *p) { return 0; } > +static inline void refrigerator(void) {} > static inline int freezing(struct task_struct *p) { return 0; } > -static inline void freeze(struct task_struct *p) { BUG(); } > -static inline int thaw_process(struct task_struct *p) { return 1; } > -static inline void frozen_process(struct task_struct *p) { BUG(); } > +static inline int try_to_freeze(void) { return 0; } > +#endif > > -static inline void refrigerator(void) {} > +#ifdef CONFIG_PM <<<< is it intentionaly? or you just lost CONFIG_MIGRATE? > +extern int freeze_processes(void); > +extern void thaw_processes(void); > +#else > static inline int freeze_processes(void) { BUG(); return 0; } > static inline void thaw_processes(void) {} > - > -static inline int try_to_freeze(void) { return 0; } > - > #endif /* CONFIG_PM */ > #endif /* __KERNEL__ */ > > Index: linux-2.6.12/kernel/power/process.c > =================================================================== > --- linux-2.6.12.orig/kernel/power/process.c 2005-06-27 05:20:15.000000000 +0000 > +++ linux-2.6.12/kernel/power/process.c 2005-06-27 15:07:46.000000000 +0000 > @@ -18,7 +18,6 @@ > */ > #define TIMEOUT (6 * HZ) > > - > static inline int freezeable(struct task_struct * p) > { > if ((p == current) || > @@ -31,28 +30,6 @@ static inline int freezeable(struct task > return 1; > } > > -/* Refrigerator is place where frozen processes are stored :-). */ > -void refrigerator(void) > -{ > - /* Hmm, should we be allowed to suspend when there are realtime > - processes around? */ > - long save; > - save = current->state; > - current->state = TASK_UNINTERRUPTIBLE; > - pr_debug("%s entered refrigerator\n", current->comm); > - printk("="); > - > - frozen_process(current); > - spin_lock_irq(¤t->sighand->siglock); > - recalc_sigpending(); /* We sent fake signal, clean it up */ > - spin_unlock_irq(¤t->sighand->siglock); > - > - while (frozen(current)) > - schedule(); > - pr_debug("%s left refrigerator\n", current->comm); > - current->state = save; > -} > - > /* 0 = success, else # of processes that we failed to stop */ > int freeze_processes(void) > { > @@ -60,6 +37,7 @@ int freeze_processes(void) > unsigned long start_time; > struct task_struct *g, *p; > > + down(&freezer_sem); > printk( "Stopping tasks: " ); > start_time = jiffies; > do { > @@ -69,12 +47,12 @@ int freeze_processes(void) > unsigned long flags; > if (!freezeable(p)) > continue; > - if ((frozen(p)) || > + if ((p->flags & PF_FROZEN) || > (p->state == TASK_TRACED) || > (p->state == TASK_STOPPED)) > continue; > > - freeze(p); > + set_thread_flag(TIF_FREEZE); > spin_lock_irqsave(&p->sighand->siglock, flags); > signal_wake_up(p, 0); > spin_unlock_irqrestore(&p->sighand->siglock, flags); > @@ -96,20 +74,6 @@ int freeze_processes(void) > > void thaw_processes(void) > { > - struct task_struct *g, *p; > - > - printk( "Restarting tasks..." ); > - read_lock(&tasklist_lock); > - do_each_thread(g, p) { > - if (!freezeable(p)) > - continue; > - if (!thaw_process(p)) > - printk(KERN_INFO " Strange, %s not stopped\n", p->comm ); > - } while_each_thread(g, p); > - > - read_unlock(&tasklist_lock); > - schedule(); > - printk( " done\n" ); > + complete_all(&thaw); > + up(&freezer_sem); > } > - > -EXPORT_SYMBOL(refrigerator); > Index: linux-2.6.12/include/asm-x86_64/thread_info.h > =================================================================== > --- linux-2.6.12.orig/include/asm-x86_64/thread_info.h 2005-06-27 05:20:15.000000000 +0000 > +++ linux-2.6.12/include/asm-x86_64/thread_info.h 2005-06-27 05:37:24.000000000 +0000 > @@ -108,6 +108,7 @@ static inline struct thread_info *stack_ > #define TIF_FORK 18 /* ret_from_fork */ > #define TIF_ABI_PENDING 19 > #define TIF_MEMDIE 20 > +#define TIF_FREEZE 21 /* Freeze process */ > > #define _TIF_SYSCALL_TRACE (1< #define _TIF_NOTIFY_RESUME (1< Index: linux-2.6.12/include/asm-ia64/thread_info.h > =================================================================== > --- linux-2.6.12.orig/include/asm-ia64/thread_info.h 2005-06-27 05:20:15.000000000 +0000 > +++ linux-2.6.12/include/asm-ia64/thread_info.h 2005-06-27 05:26:12.000000000 +0000 > @@ -76,6 +76,7 @@ struct thread_info { > #define TIF_SIGDELAYED 5 /* signal delayed from MCA/INIT/NMI/PMI context */ > #define TIF_POLLING_NRFLAG 16 /* true if poll_idle() is polling TIF_NEED_RESCHED */ > #define TIF_MEMDIE 17 > +#define TIF_FREEZE 18 /* Freeze process */ > > #define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE) > #define _TIF_SYSCALL_AUDIT (1 << TIF_SYSCALL_AUDIT) > Index: linux-2.6.12/include/asm-i386/thread_info.h > =================================================================== > --- linux-2.6.12.orig/include/asm-i386/thread_info.h 2005-06-27 05:20:15.000000000 +0000 > +++ linux-2.6.12/include/asm-i386/thread_info.h 2005-06-27 05:25:49.000000000 +0000 > @@ -143,6 +143,7 @@ register unsigned long current_stack_poi > #define TIF_SECCOMP 8 /* secure computing */ > #define TIF_POLLING_NRFLAG 16 /* true if poll_idle() is polling TIF_NEED_RESCHED */ > #define TIF_MEMDIE 17 > +#define TIF_FREEZE 18 /* Freeze thread */ > > #define _TIF_SYSCALL_TRACE (1< #define _TIF_NOTIFY_RESUME (1< Index: linux-2.6.12/include/asm-xtensa/thread_info.h > =================================================================== > --- linux-2.6.12.orig/include/asm-xtensa/thread_info.h 2005-06-27 02:23:01.000000000 +0000 > +++ linux-2.6.12/include/asm-xtensa/thread_info.h 2005-06-27 05:36:54.000000000 +0000 > @@ -118,6 +118,7 @@ static inline struct thread_info *curren > #define TIF_SINGLESTEP 4 /* restore singlestep on return to user mode */ > #define TIF_IRET 5 /* return with iret */ > #define TIF_MEMDIE 6 > +#define TIF_FREEZE 7 > #define TIF_POLLING_NRFLAG 16 /* true if poll_idle() is polling TIF_NEED_RESCHED */ > > #define _TIF_SYSCALL_TRACE (1< Index: linux-2.6.12/include/asm-h8300/thread_info.h > =================================================================== > --- linux-2.6.12.orig/include/asm-h8300/thread_info.h 2005-06-27 02:23:01.000000000 +0000 > +++ linux-2.6.12/include/asm-h8300/thread_info.h 2005-06-27 05:25:25.000000000 +0000 > @@ -94,6 +94,7 @@ static inline struct thread_info *curren > #define TIF_POLLING_NRFLAG 4 /* true if poll_idle() is polling > TIF_NEED_RESCHED */ > #define TIF_MEMDIE 5 > +#define TIF_FREEZE 6 > > /* as above, but as bit values */ > #define _TIF_SYSCALL_TRACE (1< Index: linux-2.6.12/include/asm-ppc/thread_info.h > =================================================================== > --- linux-2.6.12.orig/include/asm-ppc/thread_info.h 2005-06-27 02:23:01.000000000 +0000 > +++ linux-2.6.12/include/asm-ppc/thread_info.h 2005-06-27 05:28:53.000000000 +0000 > @@ -80,6 +80,7 @@ static inline struct thread_info *curren > #define TIF_MEMDIE 5 > #define TIF_SYSCALL_AUDIT 6 /* syscall auditing active */ > #define TIF_SECCOMP 7 /* secure computing */ > +#define TIF_FREEZE 8 > > /* as above, but as bit values */ > #define _TIF_SYSCALL_TRACE (1< Index: linux-2.6.12/include/asm-sh64/thread_info.h > =================================================================== > --- linux-2.6.12.orig/include/asm-sh64/thread_info.h 2005-06-27 02:23:01.000000000 +0000 > +++ linux-2.6.12/include/asm-sh64/thread_info.h 2005-06-27 05:35:02.000000000 +0000 > @@ -80,6 +80,7 @@ static inline struct thread_info *curren > #define TIF_SIGPENDING 2 /* signal pending */ > #define TIF_NEED_RESCHED 3 /* rescheduling necessary */ > #define TIF_MEMDIE 4 > +#define TIF_FREEZE 5 > > > #endif /* __KERNEL__ */ > Index: linux-2.6.12/include/asm-alpha/thread_info.h > =================================================================== > --- linux-2.6.12.orig/include/asm-alpha/thread_info.h 2005-06-17 19:48:29.000000000 +0000 > +++ linux-2.6.12/include/asm-alpha/thread_info.h 2005-06-27 05:23:06.000000000 +0000 > @@ -78,6 +78,7 @@ register struct thread_info *__current_t > #define TIF_UAC_NOFIX 7 > #define TIF_UAC_SIGBUS 8 > #define TIF_MEMDIE 9 > +#define TIF_FREEZE 10 > > #define _TIF_SYSCALL_TRACE (1< #define _TIF_NOTIFY_RESUME (1< Index: linux-2.6.12/include/asm-sparc/thread_info.h > =================================================================== > --- linux-2.6.12.orig/include/asm-sparc/thread_info.h 2005-06-27 02:23:01.000000000 +0000 > +++ linux-2.6.12/include/asm-sparc/thread_info.h 2005-06-27 05:35:23.000000000 +0000 > @@ -139,6 +139,7 @@ BTFIXUPDEF_CALL(void, free_thread_info, > #define TIF_POLLING_NRFLAG 9 /* true if poll_idle() is polling > * TIF_NEED_RESCHED */ > #define TIF_MEMDIE 10 > +#define TIF_FREEZE 11 > > /* as above, but as bit values */ > #define _TIF_SYSCALL_TRACE (1< Index: linux-2.6.12/include/asm-frv/thread_info.h > =================================================================== > --- linux-2.6.12.orig/include/asm-frv/thread_info.h 2005-06-27 02:23:01.000000000 +0000 > +++ linux-2.6.12/include/asm-frv/thread_info.h 2005-06-27 05:25:02.000000000 +0000 > @@ -133,6 +133,7 @@ register struct thread_info *__current_t > #define TIF_IRET 5 /* return with iret */ > #define TIF_POLLING_NRFLAG 16 /* true if poll_idle() is polling TIF_NEED_RESCHED */ > #define TIF_MEMDIE 17 /* OOM killer killed process */ > +#define TIF_FREEZE 18 > > #define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE) > #define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME) > Index: linux-2.6.12/include/asm-parisc/thread_info.h > =================================================================== > --- linux-2.6.12.orig/include/asm-parisc/thread_info.h 2005-06-27 02:23:01.000000000 +0000 > +++ linux-2.6.12/include/asm-parisc/thread_info.h 2005-06-27 05:28:34.000000000 +0000 > @@ -64,6 +64,7 @@ struct thread_info { > #define TIF_POLLING_NRFLAG 4 /* true if poll_idle() is polling TIF_NEED_RESCHED */ > #define TIF_32BIT 5 /* 32 bit binary */ > #define TIF_MEMDIE 6 > +#define TIF_FREEZE 7 > > #define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE) > #define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME) > Index: linux-2.6.12/include/asm-m68knommu/thread_info.h > =================================================================== > --- linux-2.6.12.orig/include/asm-m68knommu/thread_info.h 2005-06-27 02:23:01.000000000 +0000 > +++ linux-2.6.12/include/asm-m68knommu/thread_info.h 2005-06-27 05:27:13.000000000 +0000 > @@ -91,6 +91,7 @@ static inline struct thread_info *curren > #define TIF_POLLING_NRFLAG 4 /* true if poll_idle() is polling > TIF_NEED_RESCHED */ > #define TIF_MEMDIE 5 > +#define TIF_FREEZE 6 > > /* as above, but as bit values */ > #define _TIF_SYSCALL_TRACE (1< Index: linux-2.6.12/include/asm-m68k/thread_info.h > =================================================================== > --- linux-2.6.12.orig/include/asm-m68k/thread_info.h 2005-06-27 02:23:01.000000000 +0000 > +++ linux-2.6.12/include/asm-m68k/thread_info.h 2005-06-27 05:26:49.000000000 +0000 > @@ -49,6 +49,7 @@ struct thread_info { > #define TIF_SIGPENDING 3 /* signal pending */ > #define TIF_NEED_RESCHED 4 /* rescheduling necessary */ > #define TIF_MEMDIE 5 > +#define TIF_FREEZE 6 > > extern int thread_flag_fixme(void); > > Index: linux-2.6.12/include/asm-sh/thread_info.h > =================================================================== > --- linux-2.6.12.orig/include/asm-sh/thread_info.h 2005-06-27 02:23:01.000000000 +0000 > +++ linux-2.6.12/include/asm-sh/thread_info.h 2005-06-27 05:34:43.000000000 +0000 > @@ -84,6 +84,7 @@ static inline struct thread_info *curren > #define TIF_USEDFPU 16 /* FPU was used by this task this quantum (SMP) */ > #define TIF_POLLING_NRFLAG 17 /* true if poll_idle() is polling TIF_NEED_RESCHED */ > #define TIF_MEMDIE 18 > +#define TIF_FREEZE 19 > #define TIF_USERSPACE 31 /* true if FS sets userspace */ > > #define _TIF_SYSCALL_TRACE (1< Index: linux-2.6.12/include/asm-s390/thread_info.h > =================================================================== > --- linux-2.6.12.orig/include/asm-s390/thread_info.h 2005-06-27 02:23:01.000000000 +0000 > +++ linux-2.6.12/include/asm-s390/thread_info.h 2005-06-27 05:34:19.000000000 +0000 > @@ -102,6 +102,7 @@ static inline struct thread_info *curren > TIF_NEED_RESCHED */ > #define TIF_31BIT 18 /* 32bit process */ > #define TIF_MEMDIE 19 > +#define TIF_FREEZE 20 > > #define _TIF_SYSCALL_TRACE (1< #define _TIF_NOTIFY_RESUME (1< Index: linux-2.6.12/include/asm-arm/thread_info.h > =================================================================== > --- linux-2.6.12.orig/include/asm-arm/thread_info.h 2005-06-27 02:23:01.000000000 +0000 > +++ linux-2.6.12/include/asm-arm/thread_info.h 2005-06-27 05:23:34.000000000 +0000 > @@ -132,6 +132,7 @@ extern void iwmmxt_task_release(struct t > #define TIF_POLLING_NRFLAG 16 > #define TIF_USING_IWMMXT 17 > #define TIF_MEMDIE 18 > +#define TIF_FREEZE 19 > > #define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME) > #define _TIF_SIGPENDING (1 << TIF_SIGPENDING) > Index: linux-2.6.12/include/asm-v850/thread_info.h > =================================================================== > --- linux-2.6.12.orig/include/asm-v850/thread_info.h 2005-06-27 02:23:01.000000000 +0000 > +++ linux-2.6.12/include/asm-v850/thread_info.h 2005-06-27 05:36:25.000000000 +0000 > @@ -85,6 +85,7 @@ struct thread_info { > #define TIF_POLLING_NRFLAG 4 /* true if poll_idle() is polling > TIF_NEED_RESCHED */ > #define TIF_MEMDIE 5 > +#define TIF_FREEZE 6 > > /* as above, but as bit values */ > #define _TIF_SYSCALL_TRACE (1< Index: linux-2.6.12/include/asm-mips/thread_info.h > =================================================================== > --- linux-2.6.12.orig/include/asm-mips/thread_info.h 2005-06-27 02:23:01.000000000 +0000 > +++ linux-2.6.12/include/asm-mips/thread_info.h 2005-06-27 05:27:41.000000000 +0000 > @@ -117,6 +117,7 @@ register struct thread_info *__current_t > #define TIF_USEDFPU 16 /* FPU was used by this task this quantum (SMP) */ > #define TIF_POLLING_NRFLAG 17 /* true if poll_idle() is polling TIF_NEED_RESCHED */ > #define TIF_MEMDIE 18 > +#define TIF_FREEZE 19 > #define TIF_SYSCALL_TRACE 31 /* syscall trace active */ > > #define _TIF_SYSCALL_TRACE (1< Index: linux-2.6.12/include/asm-cris/thread_info.h > =================================================================== > --- linux-2.6.12.orig/include/asm-cris/thread_info.h 2005-06-27 02:23:01.000000000 +0000 > +++ linux-2.6.12/include/asm-cris/thread_info.h 2005-06-27 05:24:28.000000000 +0000 > @@ -86,6 +86,7 @@ struct thread_info { > #define TIF_NEED_RESCHED 3 /* rescheduling necessary */ > #define TIF_POLLING_NRFLAG 16 /* true if poll_idle() is polling TIF_NEED_RESCHED */ > #define TIF_MEMDIE 17 > +#define TIF_FREEZE 18 > > #define _TIF_SYSCALL_TRACE (1< #define _TIF_NOTIFY_RESUME (1< Index: linux-2.6.12/include/asm-arm26/thread_info.h > =================================================================== > --- linux-2.6.12.orig/include/asm-arm26/thread_info.h 2005-06-27 02:23:01.000000000 +0000 > +++ linux-2.6.12/include/asm-arm26/thread_info.h 2005-06-27 05:24:02.000000000 +0000 > @@ -127,6 +127,7 @@ extern void free_thread_info(struct thre > #define TIF_USED_FPU 16 > #define TIF_POLLING_NRFLAG 17 > #define TIF_MEMDIE 18 > +#define TIF_FREEZE 19 > > #define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME) > #define _TIF_SIGPENDING (1 << TIF_SIGPENDING) > Index: linux-2.6.12/include/asm-sparc64/thread_info.h > =================================================================== > --- linux-2.6.12.orig/include/asm-sparc64/thread_info.h 2005-06-27 02:23:01.000000000 +0000 > +++ linux-2.6.12/include/asm-sparc64/thread_info.h 2005-06-27 05:35:45.000000000 +0000 > @@ -229,6 +229,7 @@ register struct thread_info *current_thr > */ > #define TIF_ABI_PENDING 12 > #define TIF_MEMDIE 13 > +#define TIF_FREEZE 14 > > #define _TIF_SYSCALL_TRACE (1< #define _TIF_NOTIFY_RESUME (1< Index: linux-2.6.12/include/asm-m32r/thread_info.h > =================================================================== > --- linux-2.6.12.orig/include/asm-m32r/thread_info.h 2005-06-27 02:23:01.000000000 +0000 > +++ linux-2.6.12/include/asm-m32r/thread_info.h 2005-06-27 05:26:33.000000000 +0000 > @@ -156,6 +156,7 @@ static inline unsigned int get_thread_fa > #define TIF_POLLING_NRFLAG 16 /* true if poll_idle() is polling TIF_NEED_RESCHED */ > /* 31..28 fault code */ > #define TIF_MEMDIE 17 > +#define TIF_FREEZE 18 > > #define _TIF_SYSCALL_TRACE (1< #define _TIF_NOTIFY_RESUME (1< Index: linux-2.6.12/include/asm-ppc64/thread_info.h > =================================================================== > --- linux-2.6.12.orig/include/asm-ppc64/thread_info.h 2005-06-27 02:23:01.000000000 +0000 > +++ linux-2.6.12/include/asm-ppc64/thread_info.h 2005-06-27 05:29:13.000000000 +0000 > @@ -102,6 +102,7 @@ static inline struct thread_info *curren > #define TIF_SINGLESTEP 9 /* singlestepping active */ > #define TIF_MEMDIE 10 > #define TIF_SECCOMP 11 /* secure computing */ > +#define TIF_FREEZE 12 > > /* as above, but as bit values */ > #define _TIF_SYSCALL_TRACE (1< Index: linux-2.6.12/include/asm-um/thread_info.h > =================================================================== > --- linux-2.6.12.orig/include/asm-um/thread_info.h 2005-06-27 02:23:01.000000000 +0000 > +++ linux-2.6.12/include/asm-um/thread_info.h 2005-06-27 05:36:07.000000000 +0000 > @@ -72,6 +72,7 @@ static inline struct thread_info *curren > #define TIF_RESTART_BLOCK 4 > #define TIF_MEMDIE 5 > #define TIF_SYSCALL_AUDIT 6 > +#define TIF_FREEZE 7 > > #define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE) > #define _TIF_SIGPENDING (1 << TIF_SIGPENDING) > Index: linux-2.6.12/kernel/sched.c > =================================================================== > --- linux-2.6.12.orig/kernel/sched.c 2005-06-27 02:23:01.000000000 +0000 > +++ linux-2.6.12/kernel/sched.c 2005-06-27 15:08:19.000000000 +0000 > @@ -5203,6 +5203,25 @@ void __init sched_init(void) > init_idle(current, smp_processor_id()); > } > > +#if defined(CONFIG_PM) || defined(CONFIG_MIGRATE) > +DECLARE_MUTEX(freezer_sem); > +DECLARE_COMPLETION(thaw); > + > +void refrigerator(void) > +{ > + current->flags |= PF_FROZEN; > + clear_thread_flag(TIF_FREEZE); > + /* A fake signal 0 may have been sent. Recalculate sigpending */ > + spin_lock_irq(¤t->sighand->siglock); > + recalc_sigpending(); > + spin_unlock_irq(¤t->sighand->siglock); > + wait_for_completion(&thaw); > + current->flags &= ~PF_FROZEN; <<<< I still think this refrigerator is racy with freeze_processes(): <<<< scenarios: <<<< scenario 1 <<<< task1 -> freeze_processes(): taskXXX ->refrigerator() checked (task->flags & PF_FROZEN) == 0 cur->flags |= PF_FROZEN clear TIF_FREEZE set TIF_FREEZING clear PF_FROZEN <<<< so the task awakes with TIF_FREEZE flag set!!! <<<< scenario 2 <<<< look at error path in freeze_processes (on timeout), it is broken as well. You need to wakeup tasks there... <<<< ------------------------------ > +} > +EXPORT_SYMBOL(refrigerator); > +#endif > + > + > #ifdef CONFIG_DEBUG_SPINLOCK_SLEEP > void __might_sleep(char *file, int line) > { > - > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: aart@kvack.org