Messages in this thread | | | Date | Tue, 17 Nov 2015 17:19:28 +0100 | From | Oleg Nesterov <> | Subject | Re: [PATCH] mm: fix incorrect behavior when process virtual address space limit is exceeded |
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On 11/16, Piotr Kwapulinski wrote: > > @@ -1551,7 +1552,7 @@ unsigned long mmap_region(struct file *file, unsigned long addr, > * MAP_FIXED may remove pages of mappings that intersects with > * requested mapping. Account for the pages it would unmap. > */ > - if (!(vm_flags & MAP_FIXED)) > + if (!(flags & MAP_FIXED)) > return -ENOMEM;
Agree, "vm_flags & MAP_FIXED" makes no sense and just wrong...
Can't we simply remove this check? Afaics it only helps to avoid count_vma_pages_range() in the unlikely case when may_expand_vm() fails. And without MAP_FIXED count_vma_pages_range() should be cheap, find_vma_intersection() should fail.
And afaics arch/tile/mm/elf.c can use do_mmap(MAP_FIXED ...) rather than mmap_region(), it can be changed by a separate patch. In this case we can unexport mmap_region().
OTOH, I won't insist, this patch looks fine to me.
Oleg.
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