Messages in this thread Patch in this message | | | From | Shawn Bohrer <> | Subject | [PATCH] ib_umem_release should decrement mm->pinned_vm from ib_umem_get | Date | Tue, 12 Aug 2014 11:27:35 -0500 |
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From: Shawn Bohrer <sbohrer@rgmadvisors.com>
In debugging an application that receives -ENOMEM from ib_reg_mr() I found that ib_umem_get() can fail because the pinned_vm count has wrapped causing it to always be larger than the lock limit even with RLIMIT_MEMLOCK set to RLIM_INFINITY.
The wrapping of pinned_vm occurs because the process that calls ib_reg_mr() will have its mm->pinned_vm count incremented. Later a different process with a different mm_struct than the one that allocated the ib_umem struct ends up releasing it which results in decrementing the new processes mm->pinned_vm count past zero and wrapping.
I'm not entirely sure what circumstances cause a different process to release the ib_umem than the one that allocated it but the kernel stack trace of the freeing process from my situation looks like the following:
Call Trace: [<ffffffff814d64b1>] dump_stack+0x19/0x1b [<ffffffffa0b522a5>] ib_umem_release+0x1f5/0x200 [ib_core] [<ffffffffa0b90681>] mlx4_ib_destroy_qp+0x241/0x440 [mlx4_ib] [<ffffffffa0b4d93c>] ib_destroy_qp+0x12c/0x170 [ib_core] [<ffffffffa0cc7129>] ib_uverbs_close+0x259/0x4e0 [ib_uverbs] [<ffffffff81141cba>] __fput+0xba/0x240 [<ffffffff81141e4e>] ____fput+0xe/0x10 [<ffffffff81060894>] task_work_run+0xc4/0xe0 [<ffffffff810029e5>] do_notify_resume+0x95/0xa0 [<ffffffff814e3dd0>] int_signal+0x12/0x17
The following patch fixes the issue by storing the mm_struct of the process that calls ib_umem_get() so that ib_umem_release and/or ib_umem_account() can properly decrement the pinned_vm count of the correct mm_struct.
Signed-off-by: Shawn Bohrer <sbohrer@rgmadvisors.com> --- drivers/infiniband/core/umem.c | 17 ++++++++--------- 1 files changed, 8 insertions(+), 9 deletions(-)
diff --git a/drivers/infiniband/core/umem.c b/drivers/infiniband/core/umem.c index a3a2e9c..32699024 100644 --- a/drivers/infiniband/core/umem.c +++ b/drivers/infiniband/core/umem.c @@ -105,6 +105,7 @@ struct ib_umem *ib_umem_get(struct ib_ucontext *context, unsigned long addr, umem->length = size; umem->offset = addr & ~PAGE_MASK; umem->page_size = PAGE_SIZE; + umem->mm = get_task_mm(current); /* * We ask for writable memory if any access flags other than * "remote read" are set. "Local write" and "remote write" @@ -198,6 +199,7 @@ out: if (ret < 0) { if (need_release) __ib_umem_release(context->device, umem, 0); + mmput(umem->mm); kfree(umem); } else current->mm->pinned_vm = locked; @@ -229,13 +231,11 @@ static void ib_umem_account(struct work_struct *work) void ib_umem_release(struct ib_umem *umem) { struct ib_ucontext *context = umem->context; - struct mm_struct *mm; unsigned long diff; __ib_umem_release(umem->context->device, umem, 1); - mm = get_task_mm(current); - if (!mm) { + if (!umem->mm) { kfree(umem); return; } @@ -251,20 +251,19 @@ void ib_umem_release(struct ib_umem *umem) * we defer the vm_locked accounting to the system workqueue. */ if (context->closing) { - if (!down_write_trylock(&mm->mmap_sem)) { + if (!down_write_trylock(&umem->mm->mmap_sem)) { INIT_WORK(&umem->work, ib_umem_account); - umem->mm = mm; umem->diff = diff; queue_work(ib_wq, &umem->work); return; } } else - down_write(&mm->mmap_sem); + down_write(&umem->mm->mmap_sem); - current->mm->pinned_vm -= diff; - up_write(&mm->mmap_sem); - mmput(mm); + umem->mm->pinned_vm -= diff; + up_write(&umem->mm->mmap_sem); + mmput(umem->mm); kfree(umem); } EXPORT_SYMBOL(ib_umem_release); -- 1.7.7.6
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