Vivek Goyal wrote: > Got this oops while testing your patch when I did > "echo c > /proc/sysrq-trigger" That's bad :-( ... > Unable to handle kernel NULL pointer dereference at 0000000000000000 RIP: [<0000000000000000>] > <IRQ> [<ffffffff8025afd0>] handle_edge_irq+0x5c/0x127 > [<ffffffff8020e1ae>] do_IRQ+0xf1/0x15f > [<ffffffff8020c191>] ret_from_intr+0x0/0xa > <EOI> <NMI> [<ffffffff80351ae3>] __delay+0x6/0x10 > [<ffffffff8021e328>] crash_nmi_callback+0x4b/0x77 Obviously, it the oops occurs after the IRQs are re-enabled in crash_nmi_callback(). It appears that desc->chip->mask (in mask_ack_irq(), kernel/irq/chip.c:462) was NULL. I have no idea how my patch could cause that. This proves that re-enabling IRQs in this situation is too dangerous :-(. I really did hundreds of dumps in different ways (echo c>/proc/sysrq-trigger, forcing Oops and panic(), actually hititng Alt-Sysrq) and this never happened to me. Martin -- Martin Wilck PRIMERGY System Software Engineer FSC IP ESP DE6 Fujitsu Siemens Computers GmbH Heinz-Nixdorf-Ring 1 33106 Paderborn Germany Tel: ++49 5251 8 15113 Fax: ++49 5251 8 20409 Email: mailto:martin.wilck at fujitsu-siemens.com Internet: http://www.fujitsu-siemens.com Company Details: http://www.fujitsu-siemens.com/imprint.html
