lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:	Fri, 20 Feb 2009 12:08:09 +0900
From:	Tejun Heo <tj@...nel.org>
To:	Rusty Russell <rusty@...tcorp.com.au>
CC:	Ingo Molnar <mingo@...e.hu>, tglx@...utronix.de, x86@...nel.org,
	linux-kernel@...r.kernel.org, hpa@...or.com, jeremy@...p.org,
	cpw@....com
Subject: Re: [PATCHSET x86/core/percpu] implement dynamic percpu allocator

Rusty Russell wrote:
>>>> Rusty, if the fixes are fine with you i can put those two 
>>>> commits into tip/core/urgent straight away, the full string of 
>>>> 10 commits into tip/core/percpu and thus we'd avoid duplicate 
>>>> (or even conflicting) commits.
>>> No, the second one is not .29 material; it's a nice, but 
>>> theoretical, fix.
>> Can it never trigger?
> 
> Actually, checked again.  It's not even necessary AFAICT (tho a comment
> would be nice):
> 
> 	for (i = 0; i < pcpu_num_used; ptr += block_size(pcpu_size[i]), i++) {
> 		/* Extra for alignment requirement. */
> 		extra = ALIGN((unsigned long)ptr, align) - (unsigned long)ptr;
> 		BUG_ON(i == 0 && extra != 0);
> 
> 		if (pcpu_size[i] < 0 || pcpu_size[i] < extra + size)
> 			continue;
> 
> 		/* Transfer extra to previous block. */
> 		if (pcpu_size[i-1] < 0)
> 			pcpu_size[i-1] -= extra;
> 		else
> 			pcpu_size[i-1] += extra;
> 
> pcpu_size[0] is *always* negative: it's marked allocated at initialization
> (it's the static per-cpu allocations).
> 
> Sorry I didn't examine more closely,

Ah... okay.  Right.  I took the code and used it in the chunk area
allocator where 0 isn't guaranteed to be occupied and saw the problem
triggering and then assumed the modalloc allocator shared the same
problem.  So, unnecessary fix but I think it really needs some
explanation.

What to do about #tj-percpu?  Ingo, do you want me to rebase tree sans
the second one?

Thanks.

-- 
tejun
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Powered by blists - more mailing lists