Date: Thu, 20 Feb 2014 16:06:30 +0800 From: David Xu <davidxu@freebsd.org> To: Erich Dollansky <erichsfreebsdlist@alogt.com> Cc: freebsd-hackers@freebsd.org, Andre Albsmeier <mail@ma17.ata.myota.org> Subject: Re: pthread programming eats up resources (My or FreeBSD's fault?) Message-ID: <5305B786.8020708@freebsd.org> In-Reply-To: <20140220140644.7b1e0074@X220.alogt.com> References: <20140218180646.GA67861@schlappy> <53059574.8090605@freebsd.org> <20140220140644.7b1e0074@X220.alogt.com>
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On 2014/02/20 14:06, Erich Dollansky wrote:
> Hi,
>
> On Thu, 20 Feb 2014 13:41:08 +0800
> David Xu <davidxu@freebsd.org> wrote:
>
>> On 2014/02/19 02:06, Andre Albsmeier wrote:
>>
>> please compile it as static binary and run it, check if the
>> problem still exists, I am hunting the bug, it is not necessary in
>> the libthr because I have not changed its code for a long time.
>
> I just compiled is a static program. The behaviour is now different.
> The size still grows but much slower while 'res' stays below some 10MB.
>
> Size also got stagnant after some 2 min CPU time hanging around 126MB.
>
> I am running it on:
>
> FreeBSD X220.alogt.com 10.0-STABLE FreeBSD 10.0-STABLE #15 r261342: Sat
> Feb 1 14:52:39 WITA 2014
> erich@X220.alogt.com:/usr/obj/usr/src/sys/X220 amd64
>
> Erich
>
I have found the bug, it is in rtld, where malloc_aligned() is
misfunctioning, memory can be corrupted by the function.
libthr calls _rtld_allocate_tls to allocate tls control block,
the function is in rtld, its uses malloc_aligned() which is not
working correctly.
Patch is attached.
Regards,
David Xu
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Index: libexec/rtld-elf/xmalloc.c
===================================================================
--- libexec/rtld-elf/xmalloc.c (revision 260700)
+++ libexec/rtld-elf/xmalloc.c (working copy)
@@ -72,14 +72,10 @@
malloc_aligned(size_t size, size_t align)
{
void *mem, *res;
- uintptr_t x;
- size_t asize, r;
- r = round(sizeof(void *), align);
- asize = round(size, align) + r;
- mem = xmalloc(asize);
- x = (uintptr_t)mem;
- res = (void *)round(x, align);
+ mem = xmalloc(size + sizeof(void *) + align - 1);
+ res =(void*)(((uintptr_t)mem + sizeof(void *) + align - 1) &
+ ~(align - 1));
*(void **)((uintptr_t)res - sizeof(void *)) = mem;
return (res);
}
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