From: Yishai Hadas yishaih@mellanox.com
[ Upstream commit f591822c3cf314442819486f45ff7dc1f690e0c0 ]
Once implicit MR is being called to be released by ib_umem_notifier_release() its leaves were marked as "dying".
However, when dereg_mr()->mlx5_ib_free_implicit_mr()->mr_leaf_free() is called, it skips running the mr_leaf_free_action (i.e. umem_odp->work) when those leaves were marked as "dying".
As such ib_umem_release() for the leaves won't be called and their MRs will be leaked as well.
When an application exits/killed without calling dereg_mr we might hit the above flow.
This fatal scenario is reported by WARN_ON() upon mlx5_ib_dealloc_ucontext() as ibcontext->per_mm_list is not empty, the call trace can be seen below.
Originally the "dying" mark as part of ib_umem_notifier_release() was introduced to prevent pagefault_mr() from returning a success response once this happened. However, we already have today the completion mechanism so no need for that in those flows any more. Even in case a success response will be returned the firmware will not find the pages and an error will be returned in the following call as a released mm will cause ib_umem_odp_map_dma_pages() to permanently fail mmget_not_zero().
Fix the above issue by dropping the "dying" from the above flows. The other flows that are using "dying" are still needed it for their synchronization purposes.
WARNING: CPU: 1 PID: 7218 at drivers/infiniband/hw/mlx5/main.c:2004 mlx5_ib_dealloc_ucontext+0x84/0x90 [mlx5_ib] CPU: 1 PID: 7218 Comm: ibv_rc_pingpong Tainted: G E 5.2.0-rc6+ #13 Call Trace: uverbs_destroy_ufile_hw+0xb5/0x120 [ib_uverbs] ib_uverbs_close+0x1f/0x80 [ib_uverbs] __fput+0xbe/0x250 task_work_run+0x88/0xa0 do_exit+0x2cb/0xc30 ? __fput+0x14b/0x250 do_group_exit+0x39/0xb0 get_signal+0x191/0x920 ? _raw_spin_unlock_bh+0xa/0x20 ? inet_csk_accept+0x229/0x2f0 do_signal+0x36/0x5e0 ? put_unused_fd+0x5b/0x70 ? __sys_accept4+0x1a6/0x1e0 ? inet_hash+0x35/0x40 ? release_sock+0x43/0x90 ? _raw_spin_unlock_bh+0xa/0x20 ? inet_listen+0x9f/0x120 exit_to_usermode_loop+0x5c/0xc6 do_syscall_64+0x182/0x1b0 entry_SYSCALL_64_after_hwframe+0x44/0xa9
Fixes: 81713d3788d2 ("IB/mlx5: Add implicit MR support") Link: https://lore.kernel.org/r/20190805083010.21777-1-leon@kernel.org Signed-off-by: Yishai Hadas yishaih@mellanox.com Reviewed-by: Artemy Kovalyov artemyko@mellanox.com Signed-off-by: Leon Romanovsky leonro@mellanox.com Reviewed-by: Jason Gunthorpe jgg@mellanox.com Signed-off-by: Jason Gunthorpe jgg@mellanox.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/infiniband/core/umem_odp.c | 4 ---- drivers/infiniband/hw/mlx5/odp.c | 24 +++++++++--------------- 2 files changed, 9 insertions(+), 19 deletions(-)
diff --git a/drivers/infiniband/core/umem_odp.c b/drivers/infiniband/core/umem_odp.c index e4b13a32692a9..5e5f7dd82c50d 100644 --- a/drivers/infiniband/core/umem_odp.c +++ b/drivers/infiniband/core/umem_odp.c @@ -114,10 +114,6 @@ static int ib_umem_notifier_release_trampoline(struct ib_umem_odp *umem_odp, * prevent any further fault handling on this MR. */ ib_umem_notifier_start_account(umem_odp); - umem_odp->dying = 1; - /* Make sure that the fact the umem is dying is out before we release - * all pending page faults. */ - smp_wmb(); complete_all(&umem_odp->notifier_completion); umem->context->invalidate_range(umem_odp, ib_umem_start(umem), ib_umem_end(umem)); diff --git a/drivers/infiniband/hw/mlx5/odp.c b/drivers/infiniband/hw/mlx5/odp.c index 91507a2e92900..d711f3e31fa74 100644 --- a/drivers/infiniband/hw/mlx5/odp.c +++ b/drivers/infiniband/hw/mlx5/odp.c @@ -581,7 +581,6 @@ static int pagefault_mr(struct mlx5_ib_dev *dev, struct mlx5_ib_mr *mr, u32 flags) { int npages = 0, current_seq, page_shift, ret, np; - bool implicit = false; struct ib_umem_odp *odp_mr = to_ib_umem_odp(mr->umem); bool downgrade = flags & MLX5_PF_FLAGS_DOWNGRADE; bool prefetch = flags & MLX5_PF_FLAGS_PREFETCH; @@ -596,7 +595,6 @@ static int pagefault_mr(struct mlx5_ib_dev *dev, struct mlx5_ib_mr *mr, if (IS_ERR(odp)) return PTR_ERR(odp); mr = odp->private; - implicit = true; } else { odp = odp_mr; } @@ -684,19 +682,15 @@ static int pagefault_mr(struct mlx5_ib_dev *dev, struct mlx5_ib_mr *mr,
out: if (ret == -EAGAIN) { - if (implicit || !odp->dying) { - unsigned long timeout = - msecs_to_jiffies(MMU_NOTIFIER_TIMEOUT); - - if (!wait_for_completion_timeout( - &odp->notifier_completion, - timeout)) { - mlx5_ib_warn(dev, "timeout waiting for mmu notifier. seq %d against %d. notifiers_count=%d\n", - current_seq, odp->notifiers_seq, odp->notifiers_count); - } - } else { - /* The MR is being killed, kill the QP as well. */ - ret = -EFAULT; + unsigned long timeout = msecs_to_jiffies(MMU_NOTIFIER_TIMEOUT); + + if (!wait_for_completion_timeout(&odp->notifier_completion, + timeout)) { + mlx5_ib_warn( + dev, + "timeout waiting for mmu notifier. seq %d against %d. notifiers_count=%d\n", + current_seq, odp->notifiers_seq, + odp->notifiers_count); } }