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| author | Jason Gunthorpe <jgg@mellanox.com> | 2020-02-27 14:41:18 +0300 |
|---|---|---|
| committer | Jason Gunthorpe <jgg@mellanox.com> | 2020-03-04 20:56:07 +0300 |
| commit | a4e63bce1414df7ab6eb82ca9feb8494ce13e554 (patch) | |
| tree | 29db5367405979d5c353761fec56209161a1001a /drivers/infiniband | |
| parent | e38b55ea0443da35a50a3eb2079ad3612cf763b9 (diff) | |
| download | linux-a4e63bce1414df7ab6eb82ca9feb8494ce13e554.tar.xz | |
RDMA/odp: Ensure the mm is still alive before creating an implicit child
Registration of a mmu_notifier requires the caller to hold a mmget() on
the mm as registration is not permitted to race with exit_mmap(). There is
a BUG_ON inside the mmu_notifier to guard against this.
Normally creating a umem is done against current which implicitly holds
the mmget(), however an implicit ODP child is created from a pagefault
work queue and is not guaranteed to have a mmget().
Call mmget() around this registration and abort faulting if the MM has
gone to exit_mmap().
Before the patch below the notifier was registered when the implicit ODP
parent was created, so there was no chance to register a notifier outside
of current.
Fixes: c571feca2dc9 ("RDMA/odp: use mmu_notifier_get/put for 'struct ib_ucontext_per_mm'")
Link: https://lore.kernel.org/r/20200227114118.94736-1-leon@kernel.org
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Diffstat (limited to 'drivers/infiniband')
| -rw-r--r-- | drivers/infiniband/core/umem_odp.c | 24 |
1 files changed, 19 insertions, 5 deletions
diff --git a/drivers/infiniband/core/umem_odp.c b/drivers/infiniband/core/umem_odp.c index b8c657b28380..cd656ad4953b 100644 --- a/drivers/infiniband/core/umem_odp.c +++ b/drivers/infiniband/core/umem_odp.c @@ -181,14 +181,28 @@ ib_umem_odp_alloc_child(struct ib_umem_odp *root, unsigned long addr, odp_data->page_shift = PAGE_SHIFT; odp_data->notifier.ops = ops; + /* + * A mmget must be held when registering a notifier, the owming_mm only + * has a mm_grab at this point. + */ + if (!mmget_not_zero(umem->owning_mm)) { + ret = -EFAULT; + goto out_free; + } + odp_data->tgid = get_pid(root->tgid); ret = ib_init_umem_odp(odp_data, ops); - if (ret) { - put_pid(odp_data->tgid); - kfree(odp_data); - return ERR_PTR(ret); - } + if (ret) + goto out_tgid; + mmput(umem->owning_mm); return odp_data; + +out_tgid: + put_pid(odp_data->tgid); + mmput(umem->owning_mm); +out_free: + kfree(odp_data); + return ERR_PTR(ret); } EXPORT_SYMBOL(ib_umem_odp_alloc_child); |