The patch titled mm: sync vmalloc address space page tables in alloc_vm_area() has been removed from the -mm tree. Its filename was mm-sync-vmalloc-address-space-page-tables-in-alloc_vm_area.patch This patch was dropped because it was merged into mainline or a subsystem tree The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: mm: sync vmalloc address space page tables in alloc_vm_area() From: David Vrabel <david.vrabel@xxxxxxxxxx> Xen backend drivers (e.g., blkback and netback) would sometimes fail to map grant pages into the vmalloc address space allocated with alloc_vm_area(). The GNTTABOP_map_grant_ref would fail because Xen could not find the page (in the L2 table) containing the PTEs it needed to update. (XEN) mm.c:3846:d0 Could not find L1 PTE for address fbb42000 netback and blkback were making the hypercall from a kernel thread where task->active_mm != &init_mm and alloc_vm_area() was only updating the page tables for init_mm. The usual method of deferring the update to the page tables of other processes (i.e., after taking a fault) doesn't work as a fault cannot occur during the hypercall. This would work on some systems depending on what else was using vmalloc. Fix this by reverting ef691947d8a3 ("vmalloc: remove vmalloc_sync_all() from alloc_vm_area()") and add a comment to explain why it's needed. Signed-off-by: David Vrabel <david.vrabel@xxxxxxxxxx> Cc: Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx> Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> Cc: Ian Campbell <Ian.Campbell@xxxxxxxxxx> Cc: Keir Fraser <keir.xen@xxxxxxxxx> Cc: <stable@xxxxxxxxxx> [3.0.x] Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/vmalloc.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff -puN mm/vmalloc.c~mm-sync-vmalloc-address-space-page-tables-in-alloc_vm_area mm/vmalloc.c --- a/mm/vmalloc.c~mm-sync-vmalloc-address-space-page-tables-in-alloc_vm_area +++ a/mm/vmalloc.c @@ -2140,6 +2140,14 @@ struct vm_struct *alloc_vm_area(size_t s return NULL; } + /* + * If the allocated address space is passed to a hypercall + * before being used then we cannot rely on a page fault to + * trigger an update of the page tables. So sync all the page + * tables here. + */ + vmalloc_sync_all(); + return area; } EXPORT_SYMBOL_GPL(alloc_vm_area); _ Patches currently in -mm which might be from david.vrabel@xxxxxxxxxx are origin.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html