The patch titled x86: avoid theoretical vmalloc fault loop has been removed from the -mm tree. Its filename was x86-avoid-theoretical-vmalloc-fault-loop.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: x86: avoid theoretical vmalloc fault loop From: Andi Kleen <andi@xxxxxxxxxxxxxx> Ajith Kumar noticed: I was going through the vmalloc fault handling for x86_64 and am unclear about the following lines in the vmalloc_fault() function. pgd = pgd_offset(current->mm ?: &init_mm, address); pgd_ref = pgd_offset_k(address); Here the intention is to get the pgd corresponding to the current process and sync it up with the pgd in init_mm(obtained from pgd_offset_k). However, for kernel threads current->mm is NULL and hence pgd = pgd_offset(init_mm, address) = pgd_ref which means the fault handler returns without setting the pgd entry in the MM structure in the context of which the kernel thread has faulted. This could lead to never-ending faults and busy looping of kernel threads like pdflush. So, shouldn't the pgd = pgd_offset(current->mm ?: &init_mm, address); be pgd = pgd_offset(current->active_mm ?: &init_mm, address); AK: We can use active_mm unconditionally because it should be always set. Do that. Signed-off-by: Andi Kleen <ak@xxxxxxxxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: "H. Peter Anvin" <hpa@xxxxxxxxx> Cc: Nick Piggin <nickpiggin@xxxxxxxxxxxx> Cc: <stable@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- arch/x86/mm/fault.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff -puN arch/x86/mm/fault.c~x86-avoid-theoretical-vmalloc-fault-loop arch/x86/mm/fault.c --- a/arch/x86/mm/fault.c~x86-avoid-theoretical-vmalloc-fault-loop +++ a/arch/x86/mm/fault.c @@ -536,7 +536,7 @@ static int vmalloc_fault(unsigned long a happen within a race in page table update. In the later case just flush. */ - pgd = pgd_offset(current->mm ?: &init_mm, address); + pgd = pgd_offset(current->active_mm, address); pgd_ref = pgd_offset_k(address); if (pgd_none(*pgd_ref)) return -1; _ Patches currently in -mm which might be from andi@xxxxxxxxxxxxxx are origin.patch linux-next.patch x86-hpet-allow-force-enable-on-ich10-hpet.patch x86-mark-complex-bitopsh-inlines-as-__always_inline.patch nilfs2-fix-problems-of-memory-allocation-in-ioctl.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