On Sat, 2003/01/18 at 09:00:39 +0100, [EMAIL PROTECTED] wrote:
> In message <[EMAIL PROTECTED]>, Kris Kennaway writes:
>
> >I just got the following on axp1:
> >
> >panic: malloc(M_WAITOK) returned NULL
> >db_print_backtrace() at db_print_backtrace+0x18
> >panic() at panic+0x104
> >malloc() at malloc+0x1a8
> >initiate_write_inodeblock_ufs1() at initiate_write_inodeblock_ufs1+0xc4
> >softdep_disk_io_initiation() at softdep_disk_io_initiation+0xa4
> >spec_strategy() at spec_strategy+0x158
> >spec_vnoperate() at spec_vnoperate+0x2c
>
> This is a bug in the kernel memory allocator, since it should not be
> able to return NULL when M_WAITOK is specified. The potential bugs
> are more likely because M_WAITOK is defined as zero.
I found two instances of bogus M_WAITOK tests a few days ago (but
haven't received an answer from Jeff yet). The first occurance in the
attached patch would cause malloc to fail if a zone was exhausted
(without M_NOWAIT); the second one is mostly harmless.
None of the two could have caused this panic. I would guess that it
was caused by the alpha uma_small_alloc() implementation trying less
hard to allocate a page than kmem_alloc() (i.e. it does not sleep at
all). This problem does also affect the ia64 and sparc64
uma_small_alloc() versions it seems.
- Thomas
--
Thomas Moestl <[EMAIL PROTECTED]> http://www.tu-bs.de/~y0015675/
<[EMAIL PROTECTED]> http://people.FreeBSD.org/~tmm/
PGP fingerprint: 1C97 A604 2BD0 E492 51D0 9C0F 1FE6 4F1D 419C 776C
Index: uma_core.c
===================================================================
RCS file: /ncvs/src/sys/vm/uma_core.c,v
retrieving revision 1.45
diff -u -r1.45 uma_core.c
--- uma_core.c 1 Jan 2003 18:48:59 -0000 1.45
+++ uma_core.c 12 Jan 2003 23:15:49 -0000
@@ -1476,10 +1476,10 @@
zone->uz_pages >= zone->uz_maxpages) {
zone->uz_flags |= UMA_ZFLAG_FULL;
- if (flags & M_WAITOK)
- msleep(zone, &zone->uz_lock, PVM, "zonelimit", 0);
- else
+ if (flags & M_NOWAIT)
break;
+ else
+ msleep(zone, &zone->uz_lock, PVM, "zonelimit", 0);
continue;
}
zone->uz_recurse++;
@@ -1499,7 +1499,7 @@
* could have while we were unlocked. Check again before we
* fail.
*/
- if ((flags & M_WAITOK) == 0)
+ if (flags & M_NOWAIT)
flags |= M_NOVM;
}
return (slab);
@@ -1587,7 +1587,6 @@
}
/* Don't block on the next fill */
flags |= M_NOWAIT;
- flags &= ~M_WAITOK;
}
zone->uz_fills--;
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