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v0.5.1
https://github.com/torvalds/linux
02 December 2023, 22:23:51 UTC
Revision 2f60f8d3573ff90fe5d75a6d11fd2add1248e7d6 authored by Simon Derr on 05 August 2005, 02:52:03 UTC, committed by Linus Torvalds on 05 August 2005, 04:43:14 UTC 
[PATCH] __vm_enough_memory() signedness fix
 
We have found what seems to be a small bug in __vm_enough_memory() when
sysctl_overcommit_memory is set to OVERCOMMIT_NEVER.

When this bug occurs the systems fails to boot, with /sbin/init whining
about fork() returning ENOMEM.

We hunted down the problem to this:

The deferred update mecanism used in vm_acct_memory(), on a SMP system,
allows the vm_committed_space counter to have a negative value.

This should not be a problem since this counter is known to be inaccurate.

But in __vm_enough_memory() this counter is compared to the `allowed'
variable, which is an unsigned long.  This comparison is broken since it
will consider the negative values of vm_committed_space to be huge positive
values, resulting in a memory allocation failure.

Signed-off-by: <Jean-Marc.Saffroy@ext.bull.net>
Signed-off-by: <Simon.Derr@bull.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
1 parent b68e9f8
History
Tip revision: 2f60f8d3573ff90fe5d75a6d11fd2add1248e7d6 authored by Simon Derr on 05 August 2005, 02:52:03 UTC
[PATCH] __vm_enough_memory() signedness fix
Tip revision: 2f60f8d
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