The patch titled
Subject: drivers/IB,usnic: reduce scope of mmap_sem
has been added to the -mm tree. Its filename is
drivers-ibusnic-reduce-scope-of-mmap_sem.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/drivers-ibusnic-reduce-scope-of-mmap_sem.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/drivers-ibusnic-reduce-scope-of-mmap_sem.patch
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------------------------------------------------------
From: Davidlohr Bueso <dave@xxxxxxxxxxxx>
Subject: drivers/IB,usnic: reduce scope of mmap_sem
usnic_uiom_get_pages() uses gup_longterm() so we cannot really get rid of
mmap_sem altogether in the driver, but we can get rid of some complexity
that mmap_sem brings with only pinned_vm. We can get rid of the wq
altogether as we no longer need to defer work to unpin pages as the
counter is now atomic. We also share the lock.
Link: http://lkml.kernel.org/r/20190206175920.31082-6-dave@xxxxxxxxxxxx
Signed-off-by: Davidlohr Bueso <dbueso@xxxxxxx>
Reviewed-by: Ira Weiny <ira.weiny@xxxxxxxxx>
Acked-by: Parvi Kaustubhi <pkaustub@xxxxxxxxx>
Cc: Christian Benvenuti <benve@xxxxxxxxx>
Cc: Nelson Escobar <neescoba@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
--- a/drivers/infiniband/hw/usnic/usnic_ib_main.c~drivers-ibusnic-reduce-scope-of-mmap_sem
+++ a/drivers/infiniband/hw/usnic/usnic_ib_main.c
@@ -684,7 +684,6 @@ out_unreg_netdev_notifier:
out_pci_unreg:
pci_unregister_driver(&usnic_ib_pci_driver);
out_umem_fini:
- usnic_uiom_fini();
return err;
}
@@ -697,7 +696,6 @@ static void __exit usnic_ib_destroy(void
unregister_inetaddr_notifier(&usnic_ib_inetaddr_notifier);
unregister_netdevice_notifier(&usnic_ib_netdevice_notifier);
pci_unregister_driver(&usnic_ib_pci_driver);
- usnic_uiom_fini();
}
MODULE_DESCRIPTION("Cisco VIC (usNIC) Verbs Driver");
--- a/drivers/infiniband/hw/usnic/usnic_uiom.c~drivers-ibusnic-reduce-scope-of-mmap_sem
+++ a/drivers/infiniband/hw/usnic/usnic_uiom.c
@@ -47,8 +47,6 @@
#include "usnic_uiom.h"
#include "usnic_uiom_interval_tree.h"
-static struct workqueue_struct *usnic_uiom_wq;
-
#define USNIC_UIOM_PAGE_CHUNK \
((PAGE_SIZE - offsetof(struct usnic_uiom_chunk, page_list)) /\
((void *) &((struct usnic_uiom_chunk *) 0)->page_list[1] - \
@@ -127,9 +125,9 @@ static int usnic_uiom_get_pages(unsigned
npages = PAGE_ALIGN(size + (addr & ~PAGE_MASK)) >> PAGE_SHIFT;
uiomr->owning_mm = mm = current->mm;
- down_write(&mm->mmap_sem);
+ down_read(&mm->mmap_sem);
- locked = npages + atomic64_read(¤t->mm->pinned_vm);
+ locked = atomic64_add_return(npages, ¤t->mm->pinned_vm);
lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
if ((locked > lock_limit) && !capable(CAP_IPC_LOCK)) {
@@ -184,14 +182,13 @@ static int usnic_uiom_get_pages(unsigned
}
out:
- if (ret < 0)
+ if (ret < 0) {
usnic_uiom_put_pages(chunk_list, 0);
- else {
- atomic64_set(&mm->pinned_vm, locked);
+ atomic64_sub(npages, ¤t->mm->pinned_vm);
+ } else
mmgrab(uiomr->owning_mm);
- }
- up_write(&mm->mmap_sem);
+ up_read(&mm->mmap_sem);
free_page((unsigned long) page_list);
return ret;
}
@@ -435,43 +432,12 @@ static inline size_t usnic_uiom_num_page
return PAGE_ALIGN(uiomr->length + uiomr->offset) >> PAGE_SHIFT;
}
-static void usnic_uiom_release_defer(struct work_struct *work)
-{
- struct usnic_uiom_reg *uiomr =
- container_of(work, struct usnic_uiom_reg, work);
-
- down_write(&uiomr->owning_mm->mmap_sem);
- atomic64_sub(usnic_uiom_num_pages(uiomr), &uiomr->owning_mm->pinned_vm);
- up_write(&uiomr->owning_mm->mmap_sem);
-
- __usnic_uiom_release_tail(uiomr);
-}
-
void usnic_uiom_reg_release(struct usnic_uiom_reg *uiomr,
struct ib_ucontext *context)
{
__usnic_uiom_reg_release(uiomr->pd, uiomr, 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 to a workqueue.
- */
- if (context->closing) {
- if (!down_write_trylock(&uiomr->owning_mm->mmap_sem)) {
- INIT_WORK(&uiomr->work, usnic_uiom_release_defer);
- queue_work(usnic_uiom_wq, &uiomr->work);
- return;
- }
- } else {
- down_write(&uiomr->owning_mm->mmap_sem);
- }
atomic64_sub(usnic_uiom_num_pages(uiomr), &uiomr->owning_mm->pinned_vm);
- up_write(&uiomr->owning_mm->mmap_sem);
-
__usnic_uiom_release_tail(uiomr);
}
@@ -600,17 +566,5 @@ int usnic_uiom_init(char *drv_name)
return -EPERM;
}
- usnic_uiom_wq = create_workqueue(drv_name);
- if (!usnic_uiom_wq) {
- usnic_err("Unable to alloc wq for drv %s\n", drv_name);
- return -ENOMEM;
- }
-
return 0;
}
-
-void usnic_uiom_fini(void)
-{
- flush_workqueue(usnic_uiom_wq);
- destroy_workqueue(usnic_uiom_wq);
-}
--- a/drivers/infiniband/hw/usnic/usnic_uiom.h~drivers-ibusnic-reduce-scope-of-mmap_sem
+++ a/drivers/infiniband/hw/usnic/usnic_uiom.h
@@ -93,5 +93,4 @@ struct usnic_uiom_reg *usnic_uiom_reg_ge
void usnic_uiom_reg_release(struct usnic_uiom_reg *uiomr,
struct ib_ucontext *ucontext);
int usnic_uiom_init(char *drv_name);
-void usnic_uiom_fini(void);
#endif /* USNIC_UIOM_H_ */
_
Patches currently in -mm which might be from dave@xxxxxxxxxxxx are
mm-make-mm-pinned_vm-an-atomic64-counter.patch
drivers-mic-scif-do-not-use-mmap_sem.patch
drivers-ibqib-optimize-mmap_sem-usage.patch
drivers-ibhfi1-do-not-se-mmap_sem.patch
drivers-ibusnic-reduce-scope-of-mmap_sem.patch
drivers-ibcore-reduce-scope-of-mmap_sem.patch
