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authorJason Gunthorpe <jgg@mellanox.com>2019-05-23 11:08:28 -0300
committerJason Gunthorpe <jgg@mellanox.com>2019-06-18 12:11:16 -0300
commit47f245985a4f3e270b1e4f28aa49f4c939527981 (patch)
treeba0dcb5d040a33a32c50a9dbad6f467cc65f248d /include/linux/hmm.h
parent157816f3775f5c4df2c68ef0e3a100ada974aa2e (diff)
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.h26
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,