Re: [Xen-devel] kernel BUG at mm/swapfile.c:2524

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

> So back to unmap_vmas. I wonder if we are missing the lazy_unmap flag
> in 2.6.38.


> 
> >  [<c0196296>] ? unmap_vmas+0x3d6/0x820

Try the attached patch

diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index f608942..19444e6 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -2049,6 +2049,8 @@ void __init xen_init_mmu_ops(void)
        x86_init.paging.pagetable_setup_done = xen_pagetable_setup_done;
        pv_mmu_ops = xen_mmu_ops;
 
+       vmap_lazy_unmap = false;
+
        memset(dummy_mapping, 0xff, PAGE_SIZE);
 }
 
diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
index 4ed6fcd..65c3d39 100644
--- a/include/linux/vmalloc.h
+++ b/include/linux/vmalloc.h
@@ -7,6 +7,8 @@
 
 struct vm_area_struct;         /* vma defining user mapping in mm_types.h */
 
+extern bool vmap_lazy_unmap;
+
 /* bits in flags of vmalloc's vm_struct below */
 #define VM_IOREMAP     0x00000001      /* ioremap() and friends */
 #define VM_ALLOC       0x00000002      /* vmalloc() */
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index f9b1667..6ab12de 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -31,6 +31,8 @@
 #include <asm/tlbflush.h>
 #include <asm/shmparam.h>
 
+bool vmap_lazy_unmap __read_mostly = true;
+
 /*** Page table manipulation functions ***/
 
 static void vunmap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end)
@@ -501,6 +503,9 @@ static unsigned long lazy_max_pages(void)
 {
        unsigned int log;
 
+       if (!vmap_lazy_unmap)
+               return 0;
+
        log = fls(num_online_cpus());
 
        return log * (32UL * 1024 * 1024 / PAGE_SIZE);

Attachment: add_vmap_lazy_unmap.patch
Description: Text Data

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