Date: Sat, 18 Jan 2003 09:00:39 +0100 From: phk@freebsd.org To: Kris Kennaway <kris@obsecurity.org> Cc: current@freebsd.org, alpha@freebsd.org Subject: Re: panic: malloc(M_WAITOK) returned NULL Message-ID: <18381.1042876839@critter.freebsd.dk> In-Reply-To: Your message of "Fri, 17 Jan 2003 20:53:16 PST." <20030118045316.GA25224@rot13.obsecurity.org>
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In message <20030118045316.GA25224@rot13.obsecurity.org>, 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.
M_WAITOK
Indicates that it is Ok to wait for resources. It is unconve-
niently defined as 0 so care should be taken never to compare
against this value directly or try to AND it as a flag. The
default operation is to block until the memory allocation suc-
ceeds. malloc(), realloc(), and reallocf() can only return NULL
if M_NOWAIT is specified.
void *
malloc(size, type, flags)
unsigned long size;
struct malloc_type *type;
int flags;
{
[...]
if (!(flags & M_NOWAIT))
KASSERT(va != NULL, ("malloc(M_WAITOK) returned NULL"));
[...]
}
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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