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authorZhenzhong Duan <zhenzhong.duan@oracle.com>2017-09-27 02:41:25 -0700
committerBoris Ostrovsky <boris.ostrovsky@oracle.com>2017-09-28 08:26:30 -0400
commit0d805ee70a69eabd38160dc199e183ac2f13fe4b (patch)
tree51651296daca344832f29aeaf4c4448d0cb486b5 /arch
parent8c28ef3f1c1c57b6f468343d5959e5125b30334d (diff)
xen/mmu: Call xen_cleanhighmap() with 4MB aligned for page tables mapping
When bootup a PVM guest with large memory(Ex.240GB), XEN provided initial mapping overlaps with kernel module virtual space. When mapping in this space is cleared by xen_cleanhighmap(), in certain case there could be an 2MB mapping left. This is due to XEN initialize 4MB aligned mapping but xen_cleanhighmap() finish at 2MB boundary. When module loading is just on top of the 2MB space, got below warning: WARNING: at mm/vmalloc.c:106 vmap_pte_range+0x14e/0x190() Call Trace: [<ffffffff81117083>] warn_alloc_failed+0xf3/0x160 [<ffffffff81146022>] __vmalloc_area_node+0x182/0x1c0 [<ffffffff810ac91e>] ? module_alloc_update_bounds+0x1e/0x80 [<ffffffff81145df7>] __vmalloc_node_range+0xa7/0x110 [<ffffffff810ac91e>] ? module_alloc_update_bounds+0x1e/0x80 [<ffffffff8103ca54>] module_alloc+0x64/0x70 [<ffffffff810ac91e>] ? module_alloc_update_bounds+0x1e/0x80 [<ffffffff810ac91e>] module_alloc_update_bounds+0x1e/0x80 [<ffffffff810ac9a7>] move_module+0x27/0x150 [<ffffffff810aefa0>] layout_and_allocate+0x120/0x1b0 [<ffffffff810af0a8>] load_module+0x78/0x640 [<ffffffff811ff90b>] ? security_file_permission+0x8b/0x90 [<ffffffff810af6d2>] sys_init_module+0x62/0x1e0 [<ffffffff815154c2>] system_call_fastpath+0x16/0x1b Then the mapping of 2MB is cleared, finally oops when the page in that space is accessed. BUG: unable to handle kernel paging request at ffff880022600000 IP: [<ffffffff81260877>] clear_page_c_e+0x7/0x10 PGD 1788067 PUD 178c067 PMD 22434067 PTE 0 Oops: 0002 [#1] SMP Call Trace: [<ffffffff81116ef7>] ? prep_new_page+0x127/0x1c0 [<ffffffff81117d42>] get_page_from_freelist+0x1e2/0x550 [<ffffffff81133010>] ? ii_iovec_copy_to_user+0x90/0x140 [<ffffffff81119c9d>] __alloc_pages_nodemask+0x12d/0x230 [<ffffffff81155516>] alloc_pages_vma+0xc6/0x1a0 [<ffffffff81006ffd>] ? pte_mfn_to_pfn+0x7d/0x100 [<ffffffff81134cfb>] do_anonymous_page+0x16b/0x350 [<ffffffff81139c34>] handle_pte_fault+0x1e4/0x200 [<ffffffff8100712e>] ? xen_pmd_val+0xe/0x10 [<ffffffff810052c9>] ? __raw_callee_save_xen_pmd_val+0x11/0x1e [<ffffffff81139dab>] handle_mm_fault+0x15b/0x270 [<ffffffff81510c10>] do_page_fault+0x140/0x470 [<ffffffff8150d7d5>] page_fault+0x25/0x30 Call xen_cleanhighmap() with 4MB aligned for page tables mapping to fix it. The unnecessory call of xen_cleanhighmap() in DEBUG mode is also removed. -v2: add comment about XEN alignment from Juergen. References: https://lists.xen.org/archives/html/xen-devel/2012-07/msg01562.html Signed-off-by: Zhenzhong Duan <zhenzhong.duan@oracle.com> Reviewed-by: Juergen Gross <jgross@suse.com> [boris: added 'xen/mmu' tag to commit subject] Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/xen/mmu_pv.c13
1 files changed, 4 insertions, 9 deletions
diff --git a/arch/x86/xen/mmu_pv.c b/arch/x86/xen/mmu_pv.c
index 509f560bd0c6..58b09fcadbaa 100644
--- a/arch/x86/xen/mmu_pv.c
+++ b/arch/x86/xen/mmu_pv.c
@@ -1238,21 +1238,16 @@ static void __init xen_pagetable_cleanhighmap(void)
* from _brk_limit way up to the max_pfn_mapped (which is the end of
* the ramdisk). We continue on, erasing PMD entries that point to page
* tables - do note that they are accessible at this stage via __va.
- * For good measure we also round up to the PMD - which means that if
+ * As Xen is aligning the memory end to a 4MB boundary, for good
+ * measure we also round up to PMD_SIZE * 2 - which means that if
* anybody is using __ka address to the initial boot-stack - and try
* to use it - they are going to crash. The xen_start_info has been
* taken care of already in xen_setup_kernel_pagetable. */
addr = xen_start_info->pt_base;
- size = roundup(xen_start_info->nr_pt_frames * PAGE_SIZE, PMD_SIZE);
+ size = xen_start_info->nr_pt_frames * PAGE_SIZE;
- xen_cleanhighmap(addr, addr + size);
+ xen_cleanhighmap(addr, roundup(addr + size, PMD_SIZE * 2));
xen_start_info->pt_base = (unsigned long)__va(__pa(xen_start_info->pt_base));
-#ifdef DEBUG
- /* This is superfluous and is not necessary, but you know what
- * lets do it. The MODULES_VADDR -> MODULES_END should be clear of
- * anything at this stage. */
- xen_cleanhighmap(MODULES_VADDR, roundup(MODULES_VADDR, PUD_SIZE) - 1);
-#endif
}
#endif