Hi John,
John Williams wrote:
With the SLOB allocator enabled, kobjsize() doesn't seem to match
ksize(). This triggers a bug with binfmt_flat, where the do_mremap call
is used to take up slack space in the allocated text/data segments.
binfmt_flat calls ksize to get the allocated region size, but do_mremap
calls kobjsize.
I've got a system where these are reporting two different values, and
it's causing mremap to fail:
do_mremap(0x13f40000, 0x0001b4be, 0x00020000, 0x00000002,0x13f40000)
new_len is 0x00020000
kobjsize is 0x00001000
ksize is 0x00020000
Unable to allocate RAM for process text/data, errno 12
ksize() is reporting 0x20000 (and that's what binfmt_flat passed in),
but kobjsize() is reporting 0x1000. This trigggers the test in
do_mremap and the application fails with -ENOMEM.
With SLAB it's fine.
Inspired by this patch from last year
http://mailman.uclinux.org/pipermail/uclinux-dev/2006-July/039232.html
I've got the following that seems to work OK:
Index: nommu.c
===================================================================
--- nommu.c (revision 2640)
+++ nommu.c (working copy)
@@ -112,13 +112,7 @@
if (!objp || !((page = virt_to_page(objp))))
return 0;
- if (PageSlab(page))
- return ksize(objp);
-
- BUG_ON(page->index < 0);
- BUG_ON(page->index >= MAX_ORDER);
-
- return (PAGE_SIZE << page->index);
+ return ksize(objp);
}
Any thoughts? It seems that this is a known issue with SLOB.
It seems reasonable to me. Though I'd like get input from others
on lkml...
Regards
Greg
------------------------------------------------------------------------
Greg Ungerer -- Chief Software Dude EMAIL: [EMAIL PROTECTED]
SnapGear -- a Secure Computing Company PHONE: +61 7 3435 2888
825 Stanley St, FAX: +61 7 3891 3630
Woolloongabba, QLD, 4102, Australia WEB: http://www.SnapGear.com
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