On 08/10/15 07:23, Sagi Grimberg wrote:
srp_destroy_qp is designed to indicate we are safe to continue with freeing the channel resources by modifying the qp error state, posting a dummy wr on the queue-pair and waiting for it to flush. This also holds for the channel registration pool as we are unmapping the memory region when handling a scsi response. Destroying the channel registration pool before we make sure we processed all the inflight IO might introduce a use-after-free of the registration pool. This use-after-free is demonstrated in the stack trace below where srp is trying to unmap a used FMR after the fmr_pool was already destroyed. general protection fault: 0000 [#1] SMP RIP: 0010:[<ffffffff8151121b>] [<ffffffff8151121b>] _raw_spin_lock_irqsave+0x1b/0x50 Call Trace: [<ffffffffa055d88a>] ib_fmr_pool_unmap+0x1a/0xb0 [ib_core] [<ffffffffa06c00ed>] srp_unmap_data+0x17d/0x250 [ib_srp] [<ffffffffa06c01eb>] srp_free_req+0x2b/0x60 [ib_srp] [<ffffffffa06c0c94>] srp_recv_completion+0x174/0x580 [ib_srp] [<ffffffffa04580fe>] mlx4_eq_int+0x4de/0xe50 [mlx4_core] [<ffffffffa0458b00>] mlx4_msi_x_interrupt+0x10/0x20 [mlx4_core] [<ffffffff810abc45>] handle_irq_event_percpu+0x35/0x1b0 [<ffffffff810abdf2>] handle_irq_event+0x32/0x50 [<ffffffff810ae5cf>] handle_edge_irq+0x6f/0x120 [<ffffffff8100455a>] handle_irq+0x1a/0x30 [<ffffffff8151b475>] do_IRQ+0x45/0xb0 [<ffffffff8151162d>] common_interrupt+0x6d/0x6d [<ffffffff813e4d2f>] cpuidle_enter_state+0x4f/0xc0 [<ffffffff813e4e6c>] cpuidle_idle_call+0xcc/0x210 [<ffffffff8100b9ea>] arch_cpu_idle+0xa/0x30 [<ffffffff810ab1e1>] cpu_startup_entry+0xe1/0x270 [<ffffffff81030b3a>] start_secondary+0x21a/0x2c0
With which kernel version has this been observed ? scsi_remove_host() waits until all outstanding requests have finished. srp_free_ch_ib() is called either before a SCSI host is registered with the SCSI core or after scsi_remove_host() has finished. So I don't see how the above call trace could be triggered with a recent kernel ?
Bart. -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
