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. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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