* Linux-2.2.0-pre5 SMP broken on PReP?
@ 1999-01-07 18:55 Troy Benjegerdes
1999-01-11 12:26 ` Ryan Nielsen
0 siblings, 1 reply; 5+ messages in thread
From: Troy Benjegerdes @ 1999-01-07 18:55 UTC (permalink / raw
To: linuxppc-dev
After working with 2.1.132 for awhile, I decided it was time to try
Linus's 2.2.0-pre5, however I haven't been able to successfully boot with
it. I have tweaked code and tried various revisions includeing pre1 and
pre4 (pre1 wouldn't compile).
I have been getting crashes in the ncr53c8xx driver, but the dump doesn't
seem to be providing valid information.
I tracked NIP in the following dump to '<vread+280> lmw r29,20(r1)'. From
my point of view, it looks like the stack got messed up somewhere.
I am also building this kernel in a CONFIG_SMP=y configuration since I am
going to work on MTX SMP once the kernel runs again ;).
ncr53c8xx: at PCI bus 0, device 12, function 0
ncr53c8xx: reallocating base (Wacky IBM)ncr53c8xx: reallocating base2
(Wacky IBM)<
ncr53c875-0: rev=0x04, base=0x1fffe00, io_port=0xffffe00, irq=14
ncr53c875-0: NCR clock is 26691KHz, 26772KHz
ncr53c875-0: ID 7, Fast-20, Parity Checking
ncr53c875-0: on-chip RAM at 0x1ffe000
ncr53c875-0: restart (scsi reset).
ncr53c875-0: Downloading SCSI SCRIPTS.
scsi0 : ncr53c8xx - revision 3.1d
scsi : 1 host.
NIP: C00246F8 XER: 00000000 LR: C0024634 REGS: c7ffff00 TRAP: 0300
MSR: 00009032 EE: 1 PR: 0 FP: 0 ME: 1 IR/DR: 11
TASK = c03b0000[3] 'kswapd' mm->pgd c0128000 Last syscall: -1
last math 00000000 CPU: 0 last CPU: 0
GPR00: C0024634 C7FFFFF0 C03B0000 7BDFFFE0 FFFFFFFF 00000000 FFFFFC18 00000000
GPR08: 00000000 C0160000 00008000 C03B1F10 84200020 00000000 00000000 00000000
GPR16: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
GPR24: 00000000 C0133330 C0140000 C0140000 C0170000 00000000 00000000 00000000
Call backtrace:
00000000
Instruction DUMP: 2c870000 4086ff34 7c6c4050 <bba10014> 38210020 4e800020 9421
Kernel panic: kernel access of bad area pc c00246f8 lr c0024634 address C8000004 t3
Rebooting in 180 seconds..global_restore_flags: 00000042 (00418570)
--------------------------------------------------------------------------
| Troy Benjegerdes | troy@microux.com | hozer@drgw.net |
| Unix is user friendly... You just have to be friendly to it first. |
| This message composed with 100% free software. http://www.gnu.org |
--------------------------------------------------------------------------
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^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: Linux-2.2.0-pre5 SMP broken on PReP?
1999-01-07 18:55 Linux-2.2.0-pre5 SMP broken on PReP? Troy Benjegerdes
@ 1999-01-11 12:26 ` Ryan Nielsen
1999-01-11 16:29 ` Benjamin Herrenschmidt
1999-01-11 16:54 ` Troy Benjegerdes
0 siblings, 2 replies; 5+ messages in thread
From: Ryan Nielsen @ 1999-01-11 12:26 UTC (permalink / raw
To: Troy Benjegerdes; +Cc: linuxppc-dev
On Thu, Jan 07, 1999 at 12:55:22 -0600, Troy Benjegerdes wrote:
>
> After working with 2.1.132 for awhile, I decided it was time to try
> Linus's 2.2.0-pre5, however I haven't been able to successfully boot with
> it. I have tweaked code and tried various revisions includeing pre1 and
> pre4 (pre1 wouldn't compile).
>
> I have been getting crashes in the ncr53c8xx driver, but the dump doesn't
> seem to be providing valid information.
it is crashing in kswapd, not the ncr driver.
I got pre6 to work by reverse-patching the kswapd part of mm/vmscan.c down to pre4
this is only needed for SMP...
--- vmscan.c Mon Jan 11 03:50:23 1999
+++ vmscan.c.works Mon Jan 11 03:41:35 1999
@@ -20,6 +20,13 @@
#include <asm/pgtable.h>
+/*
+ * The wait queue for waking up the pageout daemon:
+ */
+static struct task_struct * kswapd_task = NULL;
+
+static void init_swap_timer(void);
+
/*
* The swap-out functions return 1 if they successfully
* threw something out, and we got a free page. It returns
@@ -385,36 +392,71 @@
printk ("Starting kswapd v%.*s\n", i, s);
}
+#define free_memory(fn) \
+ count++; do { if (!--count) goto done; } while (fn)
+
+static int kswapd_free_pages(int kswapd_state)
+{
+ unsigned long end_time;
+
+ /* Always trim SLAB caches when memory gets low. */
+ kmem_cache_reap(0);
+
+ /* max one hundreth of a second */
+ end_time = jiffies + (HZ-1)/100;
+ do {
+ int priority = 8;
+ int count = pager_daemon.swap_cluster;
+
+ switch (kswapd_state) {
+ do {
+ default:
+ free_memory(shrink_mmap(priority, 0));
+ free_memory(swap_out(priority, 0));
+ kswapd_state++;
+ case 1:
+ free_memory(shm_swap(priority, 0));
+ shrink_dcache_memory(priority, 0);
+ kswapd_state = 0;
+ } while (--priority >= 0);
+ return kswapd_state;
+ }
+done:
+ if (nr_free_pages > freepages.high + pager_daemon.swap_cluster)
+ break;
+ } while (time_before_eq(jiffies,end_time));
+ return kswapd_state;
+}
+
/*
- * The background pageout daemon, started as a kernel thread
- * from the init process.
- *
- * This basically executes once a second, trickling out pages
- * so that we have _some_ free memory available even if there
- * is no other activity that frees anything up. This is needed
- * for things like routing etc, where we otherwise might have
- * all activity going on in asynchronous contexts that cannot
- * page things out.
- *
- * If there are applications that are active memory-allocators
- * (most normal use), this basically shouldn't matter.
+ * The background pageout daemon.
+ * Started as a kernel thread from the init process.
*/
int kswapd(void *unused)
{
current->session = 1;
current->pgrp = 1;
strcpy(current->comm, "kswapd");
+ sigfillset(¤t->blocked);
+
+ /*
+ * As a kernel thread we want to tamper with system buffers
+ * and other internals and thus be subject to the SMP locking
+ * rules. (On a uniprocessor box this does nothing).
+ */
+ lock_kernel();
/*
- * Hey, if somebody wants to kill us, be our guest.
- * Don't come running to mama if things don't work.
+ * Set the base priority to something smaller than a
+ * regular process. We will scale up the priority
+ * dynamically depending on how much memory we need.
*/
- siginitsetinv(¤t->blocked, sigmask(SIGKILL));
-
+ current->priority = (DEF_PRIORITY * 2) / 3;
+
/*
* Tell the memory management that we're a "memory allocator",
* and that if we need more memory we should get access to it
- * regardless (see "__get_free_pages()"). "kswapd" should
+ * regardless (see "try_to_free_pages()"). "kswapd" should
* never get caught in the normal page freeing logic.
*
* (Kswapd normally doesn't need memory anyway, but sometimes
@@ -425,23 +467,21 @@
*/
current->flags |= PF_MEMALLOC;
+ init_swap_timer();
+ kswapd_task = current;
while (1) {
- if (signal_pending(current))
- break;
+ int state = 0;
+
current->state = TASK_INTERRUPTIBLE;
+ flush_signals(current);
run_task_queue(&tq_disk);
- schedule_timeout(HZ);
-
- /*
- * kswapd isn't even meant to keep up with anything,
- * so just a few pages per second is plenty: the only
- * point is to make sure that the system doesn't stay
- * forever in a really bad memory squeeze.
- */
- if (nr_free_pages < freepages.high)
- try_to_free_pages(0, 16);
+ schedule();
+ swapstats.wakeups++;
+ state = kswapd_free_pages(state);
}
-
+ /* As if we could ever get here - maybe we want to make this killable */
+ kswapd_task = NULL;
+ unlock_kernel();
return 0;
}
@@ -488,4 +528,73 @@
unlock_kernel();
return priority >= 0;
+}
+
+/*
+ * Wake up kswapd according to the priority
+ * 0 - no wakeup
+ * 1 - wake up as a low-priority process
+ * 2 - wake up as a normal process
+ * 3 - wake up as an almost real-time process
+ *
+ * This plays mind-games with the "goodness()"
+ * function in kernel/sched.c.
+ */
+static inline void kswapd_wakeup(struct task_struct *p, int priority)
+{
+ if (priority) {
+ p->counter = p->priority << priority;
+ wake_up_process(p);
+ }
+}
+
+/*
+ * The swap_tick function gets called on every clock tick.
+ */
+void swap_tick(void)
+{
+ struct task_struct *p = kswapd_task;
+
+ /*
+ * Only bother to try to wake kswapd up
+ * if the task exists and can be woken.
+ */
+ if (p && (p->state & TASK_INTERRUPTIBLE)) {
+ unsigned int pages;
+ int want_wakeup;
+
+ /*
+ * Schedule for wakeup if there isn't lots
+ * of free memory or if there is too much
+ * of it used for buffers or pgcache.
+ *
+ * "want_wakeup" is our priority: 0 means
+ * not to wake anything up, while 3 means
+ * that we'd better give kswapd a realtime
+ * priority.
+ */
+ want_wakeup = 0;
+ pages = nr_free_pages;
+ if (pages < freepages.high)
+ want_wakeup = 1;
+ if (pages < freepages.low)
+ want_wakeup = 2;
+ if (pages < freepages.min)
+ want_wakeup = 3;
+
+ kswapd_wakeup(p,want_wakeup);
+ }
+
+ timer_active |= (1<<SWAP_TIMER);
+}
+
+/*
+ * Initialise the swap timer
+ */
+
+void init_swap_timer(void)
+{
+ timer_table[SWAP_TIMER].expires = jiffies;
+ timer_table[SWAP_TIMER].fn = swap_tick;
+ timer_active |= (1<<SWAP_TIMER);
}
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^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: Linux-2.2.0-pre5 SMP broken on PReP?
1999-01-11 12:26 ` Ryan Nielsen
@ 1999-01-11 16:29 ` Benjamin Herrenschmidt
1999-01-12 2:43 ` Ryan Nielsen
1999-01-11 16:54 ` Troy Benjegerdes
1 sibling, 1 reply; 5+ messages in thread
From: Benjamin Herrenschmidt @ 1999-01-11 16:29 UTC (permalink / raw
To: linuxppc-dev, Ryan Nielsen
On Mon, Jan 11, 1999, Ryan Nielsen <ran@krazynet.com> wrote:
>it is crashing in kswapd, not the ncr driver.
>
>I got pre6 to work by reverse-patching the kswapd part of mm/vmscan.c down to
>pre4
>this is only needed for SMP...
Linus posted some messages about this on the kernel ML, pre-7 should fix
all that mess, the memory trashing may finally work fine after all ;-)
--
E-Mail: <mailto:bh40@calva.net>
BenH. Web : <http://calvaweb.calvacom.fr/bh40/>
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^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: Linux-2.2.0-pre5 SMP broken on PReP?
1999-01-11 12:26 ` Ryan Nielsen
1999-01-11 16:29 ` Benjamin Herrenschmidt
@ 1999-01-11 16:54 ` Troy Benjegerdes
1 sibling, 0 replies; 5+ messages in thread
From: Troy Benjegerdes @ 1999-01-11 16:54 UTC (permalink / raw
To: Ryan Nielsen; +Cc: linuxppc-dev
On Mon, 11 Jan 1999, Ryan Nielsen wrote:
> On Thu, Jan 07, 1999 at 12:55:22 -0600, Troy Benjegerdes wrote:
> >
> > After working with 2.1.132 for awhile, I decided it was time to try
> > Linus's 2.2.0-pre5, however I haven't been able to successfully boot with
> > it. I have tweaked code and tried various revisions includeing pre1 and
> > pre4 (pre1 wouldn't compile).
> >
> > I have been getting crashes in the ncr53c8xx driver, but the dump doesn't
> > seem to be providing valid information.
>
> it is crashing in kswapd, not the ncr driver.
I suppose I meant 'while starting the ncr driver'. At the time I wasn't
convinced the dump was valid.
Do you (or anyone else) have idea why this patch makes things work again?
Is anyone running pre6 on an SMP box? There are very few SMP-only
references in this patch. Is there something in arch/ppc/mm that needs
updating?
>
> I got pre6 to work by reverse-patching the kswapd part of mm/vmscan.c down to pre4
> this is only needed for SMP...
--------------------------------------------------------------------------
| Troy Benjegerdes | troy@microux.com | hozer@drgw.net |
| Unix is user friendly... You just have to be friendly to it first. |
| This message composed with 100% free software. http://www.gnu.org |
--------------------------------------------------------------------------
[[ This message was sent via the linuxppc-dev mailing list. Replies are ]]
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^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: Linux-2.2.0-pre5 SMP broken on PReP?
1999-01-11 16:29 ` Benjamin Herrenschmidt
@ 1999-01-12 2:43 ` Ryan Nielsen
0 siblings, 0 replies; 5+ messages in thread
From: Ryan Nielsen @ 1999-01-12 2:43 UTC (permalink / raw
To: Benjamin Herrenschmidt; +Cc: linuxppc-dev
Benjamin Herrenschmidt wrote:
> On Mon, Jan 11, 1999, Ryan Nielsen <ran@krazynet.com> wrote:
>
> >it is crashing in kswapd, not the ncr driver.
> >
> >I got pre6 to work by reverse-patching the kswapd part of mm/vmscan.c down to
> >pre4
> >this is only needed for SMP...
>
> Linus posted some messages about this on the kernel ML, pre-7 should fix
> all that mess, the memory trashing may finally work fine after all ;-)
He didn't mention SMP/PPC/kswapd, as far as i saw, only try_to_free_pages() etc.
I tried pre-7.gz and it made no difference, reverse-patching kswapd still makes things work.
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^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~1999-01-12 2:43 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz follow: Atom feed
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1999-01-07 18:55 Linux-2.2.0-pre5 SMP broken on PReP? Troy Benjegerdes
1999-01-11 12:26 ` Ryan Nielsen
1999-01-11 16:29 ` Benjamin Herrenschmidt
1999-01-12 2:43 ` Ryan Nielsen
1999-01-11 16:54 ` Troy Benjegerdes
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