On Wed, May 15, 2013 at 07:46:36AM -0500, Cliff Wickman wrote: > > /proc/<pid>/smaps and similar walks through a user page table should not > be looking at VM_PFNMAP areas. > > v2: > - moves the VM_BUG_ON out of the loop > - adds the needed test for vma->vm_start <= addr > > v3 adds comments to make this clearer, as N. Horiguchi recommends: > > I recommend that you check VM_PFNMAP in the possible callers' side. > > But this patch seems to solve your problem, so with properly commenting > > this somewhere, I do not oppose it. > > Certain tests in walk_page_range() (specifically split_huge_page_pmd()) > assume that all the mapped PFN's are backed with page structures. And this is > not usually true for VM_PFNMAP areas. This can result in panics on kernel > page faults when attempting to address those page structures. > > There are a half dozen callers of walk_page_range() that walk through > a task's entire page table (as N. Horiguchi pointed out). So rather than > change all of them, this patch changes just walk_page_range() to ignore > VM_PFNMAP areas. > > The logic of hugetlb_vma() is moved back into walk_page_range(), as we > want to test any vma in the range. > > VM_PFNMAP areas are used by: > - graphics memory manager gpu/drm/drm_gem.c > - global reference unit sgi-gru/grufile.c > - sgi special memory char/mspec.c > - and probably several out-of-tree modules > > I'm copying everyone who has changed this file recently, in case > there is some reason that I am not aware of to provide > /proc/<pid>/smaps|clear_refs|maps|numa_maps for these VM_PFNMAP areas. > > Signed-off-by: Cliff Wickman <[email protected]>
Thank you. Reviewed-by: Naoya Horiguchi <[email protected]> -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
