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| author |   Jason Gunthorpe <jgg@mellanox.com> | 2019-05-23 11:08:28 -0300 |
|---|---|---|
| committer | Jason Gunthorpe <jgg@mellanox.com> | 2019-06-18 12:11:16 -0300 |
| commit | 47f245985a4f3e270b1e4f28aa49f4c939527981 (patch) | |
| tree | ba0dcb5d040a33a32c50a9dbad6f467cc65f248d /include/linux/hmm.h | |
| parent | mm/hmm: Do not use list*_rcu() for hmm->ranges (diff) | |
| download | linux-dev-47f245985a4f3e270b1e4f28aa49f4c939527981.tar.xz linux-dev-47f245985a4f3e270b1e4f28aa49f4c939527981.zip | |
mm/hmm: Hold on to the mmget for the lifetime of the range
Range functions like hmm_range_snapshot() and hmm_range_fault() call
find_vma, which requires hodling the mmget() and the mmap_sem for the mm.
Make this simpler for the callers by holding the mmget() inside the range
for the lifetime of the range. Other functions that accept a range should
only be called if the range is registered.
This has the side effect of directly preventing hmm_release() from
happening while a range is registered. That means range->dead cannot be
false during the lifetime of the range, so remove dead and
hmm_mirror_mm_is_alive() entirely.
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Reviewed-by: Ralph Campbell <rcampbell@nvidia.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Tested-by: Philip Yang <Philip.Yang@amd.com>
Diffstat (limited to 'include/linux/hmm.h')
| -rw-r--r-- | include/linux/hmm.h | 26 |
1 files changed, 0 insertions, 26 deletions
diff --git a/include/linux/hmm.h b/include/linux/hmm.h index 26e7c477490c..bf013e965257 100644 --- a/include/linux/hmm.h +++ b/include/linux/hmm.h @@ -82,7 +82,6 @@ * @mirrors_sem: read/write semaphore protecting the mirrors list * @wq: wait queue for user waiting on a range invalidation * @notifiers: count of active mmu notifiers - * @dead: is the mm dead ? */ struct hmm { struct mm_struct *mm; @@ -95,7 +94,6 @@ struct hmm { wait_queue_head_t wq; struct rcu_head rcu; long notifiers; - bool dead; }; /* @@ -460,30 +458,6 @@ int hmm_mirror_register(struct hmm_mirror *mirror, struct mm_struct *mm); void hmm_mirror_unregister(struct hmm_mirror *mirror); /* - * hmm_mirror_mm_is_alive() - test if mm is still alive - * @mirror: the HMM mm mirror for which we want to lock the mmap_sem - * Return: false if the mm is dead, true otherwise - * - * This is an optimization, it will not always accurately return false if the - * mm is dead; i.e., there can be false negatives (process is being killed but - * HMM is not yet informed of that). It is only intended to be used to optimize - * out cases where the driver is about to do something time consuming and it - * would be better to skip it if the mm is dead. - */ -static inline bool hmm_mirror_mm_is_alive(struct hmm_mirror *mirror) -{ - struct mm_struct *mm; - - if (!mirror || !mirror->hmm) - return false; - mm = READ_ONCE(mirror->hmm->mm); - if (mirror->hmm->dead || !mm) - return false; - - return true; -} - -/* * Please see Documentation/vm/hmm.rst for how to use the range API. */ int hmm_range_register(struct hmm_range *range, |