On 03/09, Borislav Petkov wrote: > > On Sat, Mar 07, 2015 at 04:38:44PM +0100, Oleg Nesterov wrote: > > math_state_restore() assumes it is called with irqs disabled, but > > this is not true if the caller is __restore_xstate_sig(). > > > > This means that if ia32_fxstate == T and __copy_from_user() fails > > __restore_xstate_sig() returns with irqs disabled too. This trgiggers > > > > BUG: sleeping function called from invalid context at > > kernel/locking/rwsem.c:41 > > [<ffffffff81381499>] dump_stack+0x59/0xa0 > > [<ffffffff8106bd05>] ___might_sleep+0x105/0x110 > > [<ffffffff8138786d>] ? _raw_spin_unlock_irqrestore+0x3d/0x70 > > [<ffffffff8106bd8d>] __might_sleep+0x7d/0xb0 > > [<ffffffff81385426>] down_read+0x26/0xa0 > > [<ffffffff8138788a>] ? _raw_spin_unlock_irqrestore+0x5a/0x70 > > [<ffffffff81136038>] print_vma_addr+0x58/0x130 > > [<ffffffff8100239e>] signal_fault+0xbe/0xf0 > > [<ffffffff810419aa>] sys32_rt_sigreturn+0xba/0xd0 > > > > Change __restore_xstate_sig() to call set_used_math() unconditionally, > > this avoids sti/cli in math_state_restore(). If copy_from_user() fails > > we can simply do fpu_finit() by hand. > > > > Note: this is only the first step. math_state_restore() should not check > > used_math(), it should set this flag. While init_fpu() should simply die. > > > > Signed-off-by: Oleg Nesterov <o...@redhat.com> > > Cc: <sta...@vger.kernel.org> > > Makes sense to me. I guess we should wait for Dave to test first though...
The patch only fixes the problem with irqs disabled, I tested this. The problem with fpu_init/XRSTORS is another thing... Oleg. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
