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drivers/IB,core: reduce scope of mmap_sem

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ib_umem_get() uses gup_longterm() and relies on the lock to stabilze the
vma_list, so we cannot really get rid of mmap_sem altogether, but now that
the counter is atomic, we can get of some complexity that mmap_sem brings
with only pinned_vm.

Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
This commit is contained in:
Davidlohr Bueso 2019-02-06 09:59:20 -08:00 committed by Jason Gunthorpe
parent 8ea1f989aa
commit b95df5e3e4
1 changed files with 2 additions and 39 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

41
drivers/infiniband/core/umem.c
View file

@ -165,15 +165,12 @@ struct ib_umem *ib_umem_get(struct ib_udata *udata, unsigned long addr,
lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
down_write(&mm->mmap_sem);
new_pinned = atomic64_read(&mm->pinned_vm) + npages;
new_pinned = atomic64_add_return(npages, &mm->pinned_vm);
if (new_pinned > lock_limit && !capable(CAP_IPC_LOCK)) {
up_write(&mm->mmap_sem);
atomic64_sub(npages, &mm->pinned_vm);
ret = -ENOMEM;
goto out;
}
atomic64_set(&mm->pinned_vm, new_pinned);
up_write(&mm->mmap_sem);
cur_base = addr & PAGE_MASK;
@ -233,9 +230,7 @@ struct ib_umem *ib_umem_get(struct ib_udata *udata, unsigned long addr,
umem_release:
__ib_umem_release(context->device, umem, 0);
vma:
down_write(&mm->mmap_sem);
atomic64_sub(ib_umem_num_pages(umem), &mm->pinned_vm);
up_write(&mm->mmap_sem);
out:
if (vma_list)
free_page((unsigned long) vma_list);
@ -258,25 +253,12 @@ static void __ib_umem_release_tail(struct ib_umem *umem)
kfree(umem);
}
static void ib_umem_release_defer(struct work_struct *work)
{
struct ib_umem *umem = container_of(work, struct ib_umem, work);
down_write(&umem->owning_mm->mmap_sem);
atomic64_sub(ib_umem_num_pages(umem), &umem->owning_mm->pinned_vm);
up_write(&umem->owning_mm->mmap_sem);
__ib_umem_release_tail(umem);
}
/**
* ib_umem_release - release memory pinned with ib_umem_get
* @umem: umem struct to release
*/
void ib_umem_release(struct ib_umem *umem)
{
struct ib_ucontext *context = umem->context;
if (umem->is_odp) {
ib_umem_odp_release(to_ib_umem_odp(umem));
__ib_umem_release_tail(umem);
@ -285,26 +267,7 @@ void ib_umem_release(struct ib_umem *umem)
__ib_umem_release(umem->context->device, umem, 1);
/*
* We may be called with the mm's mmap_sem already held. This
* can happen when a userspace munmap() is the call that drops
* the last reference to our file and calls our release
* method. If there are memory regions to destroy, we'll end
* up here and not be able to take the mmap_sem. In that case
* we defer the vm_locked accounting a workqueue.
*/
if (context->closing) {
if (!down_write_trylock(&umem->owning_mm->mmap_sem)) {
INIT_WORK(&umem->work, ib_umem_release_defer);
queue_work(ib_wq, &umem->work);
return;
}
} else {
down_write(&umem->owning_mm->mmap_sem);
}
atomic64_sub(ib_umem_num_pages(umem), &umem->owning_mm->pinned_vm);
up_write(&umem->owning_mm->mmap_sem);
__ib_umem_release_tail(umem);
}
EXPORT_SYMBOL(ib_umem_release);