linux/arch/ia64/mm
Hugh Dickins 68589bc353 [PATCH] hugetlb: prepare_hugepage_range check offset too
(David:)

If hugetlbfs_file_mmap() returns a failure to do_mmap_pgoff() - for example,
because the given file offset is not hugepage aligned - then do_mmap_pgoff
will go to the unmap_and_free_vma backout path.

But at this stage the vma hasn't been marked as hugepage, and the backout path
will call unmap_region() on it.  That will eventually call down to the
non-hugepage version of unmap_page_range().  On ppc64, at least, that will
cause serious problems if there are any existing hugepage pagetable entries in
the vicinity - for example if there are any other hugepage mappings under the
same PUD.  unmap_page_range() will trigger a bad_pud() on the hugepage pud
entries.  I suspect this will also cause bad problems on ia64, though I don't
have a machine to test it on.

(Hugh:)

prepare_hugepage_range() should check file offset alignment when it checks
virtual address and length, to stop MAP_FIXED with a bad huge offset from
unmapping before it fails further down.  PowerPC should apply the same
prepare_hugepage_range alignment checks as ia64 and all the others do.

Then none of the alignment checks in hugetlbfs_file_mmap are required (nor
is the check for too small a mapping); but even so, move up setting of
VM_HUGETLB and add a comment to warn of what David Gibson discovered - if
hugetlbfs_file_mmap fails before setting it, do_mmap_pgoff's unmap_region
when unwinding from error will go the non-huge way, which may cause bad
behaviour on architectures (powerpc and ia64) which segregate their huge
mappings into a separate region of the address space.

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Acked-by: Adam Litke <agl@us.ibm.com>
Acked-by: David Gibson <david@gibson.dropbear.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-11-14 09:09:27 -08:00
..
Makefile [PATCH] ia64: ioremap: check EFI for valid memory attributes 2006-03-26 08:56:54 -08:00
contig.c [PATCH] mm: use symbolic names instead of indices for zone initialisation 2006-10-11 11:14:14 -07:00
discontig.c [PATCH] mm: use symbolic names instead of indices for zone initialisation 2006-10-11 11:14:14 -07:00
extable.c Remove obsolete #include <linux/config.h> 2006-06-30 19:25:36 +02:00
fault.c [PATCH] pidspace: is_init() 2006-09-29 09:18:12 -07:00
hugetlbpage.c [PATCH] hugetlb: prepare_hugepage_range check offset too 2006-11-14 09:09:27 -08:00
init.c [PATCH] Have ia64 use add_active_range() and free_area_init_nodes 2006-09-27 08:26:11 -07:00
ioremap.c [IA64] sparse cleanups 2006-08-02 16:03:44 -07:00
numa.c [PATCH] hot-add-mem x86_64: memory_add_physaddr_to_nid node fixup 2006-10-01 00:39:18 -07:00
tlb.c Remove obsolete #include <linux/config.h> 2006-06-30 19:25:36 +02:00