IB: Put rlimit accounting struct in struct ib_umem
When memory pinned with ib_umem_get() is released, ib_umem_release()
needs to subtract the amount of memory being unpinned from
mm->locked_vm. However, ib_umem_release() may be called with
mm->mmap_sem already held for writing if the memory is being released
as part of an munmap() call, so it is sometimes necessary to defer
this accounting into a workqueue.
However, the work struct used to defer this accounting is dynamically
allocated before it is queued, so there is the possibility of failing
that allocation. If the allocation fails, then ib_umem_release has no
choice except to bail out and leave the process with a permanently
elevated locked_vm.
Fix this by allocating the structure to defer accounting as part of
the original struct ib_umem, so there's no possibility of failing a
later allocation if creating the struct ib_umem and pinning memory
succeeds.
Signed-off-by: Roland Dreier <rolandd@cisco.com>
diff --git a/drivers/infiniband/core/umem.c b/drivers/infiniband/core/umem.c
index 48e854c..f32ca5f 100644
--- a/drivers/infiniband/core/umem.c
+++ b/drivers/infiniband/core/umem.c
@@ -39,13 +39,6 @@
#include "uverbs.h"
-struct ib_umem_account_work {
- struct work_struct work;
- struct mm_struct *mm;
- unsigned long diff;
-};
-
-
static void __ib_umem_release(struct ib_device *dev, struct ib_umem *umem, int dirty)
{
struct ib_umem_chunk *chunk, *tmp;
@@ -192,16 +185,15 @@
}
EXPORT_SYMBOL(ib_umem_get);
-static void ib_umem_account(struct work_struct *_work)
+static void ib_umem_account(struct work_struct *work)
{
- struct ib_umem_account_work *work =
- container_of(_work, struct ib_umem_account_work, work);
+ struct ib_umem *umem = container_of(work, struct ib_umem, work);
- down_write(&work->mm->mmap_sem);
- work->mm->locked_vm -= work->diff;
- up_write(&work->mm->mmap_sem);
- mmput(work->mm);
- kfree(work);
+ down_write(&umem->mm->mmap_sem);
+ umem->mm->locked_vm -= umem->diff;
+ up_write(&umem->mm->mmap_sem);
+ mmput(umem->mm);
+ kfree(umem);
}
/**
@@ -210,7 +202,6 @@
*/
void ib_umem_release(struct ib_umem *umem)
{
- struct ib_umem_account_work *work;
struct ib_ucontext *context = umem->context;
struct mm_struct *mm;
unsigned long diff;
@@ -222,7 +213,6 @@
return;
diff = PAGE_ALIGN(umem->length + umem->offset) >> PAGE_SHIFT;
- kfree(umem);
/*
* We may be called with the mm's mmap_sem already held. This
@@ -233,17 +223,11 @@
* we defer the vm_locked accounting to the system workqueue.
*/
if (context->closing && !down_write_trylock(&mm->mmap_sem)) {
- work = kmalloc(sizeof *work, GFP_KERNEL);
- if (!work) {
- mmput(mm);
- return;
- }
+ INIT_WORK(&umem->work, ib_umem_account);
+ umem->mm = mm;
+ umem->diff = diff;
- INIT_WORK(&work->work, ib_umem_account);
- work->mm = mm;
- work->diff = diff;
-
- schedule_work(&work->work);
+ schedule_work(&umem->work);
return;
} else
down_write(&mm->mmap_sem);
@@ -251,6 +235,7 @@
current->mm->locked_vm -= diff;
up_write(&mm->mmap_sem);
mmput(mm);
+ kfree(umem);
}
EXPORT_SYMBOL(ib_umem_release);
diff --git a/include/rdma/ib_umem.h b/include/rdma/ib_umem.h
index 06307f7..b3a36f7 100644
--- a/include/rdma/ib_umem.h
+++ b/include/rdma/ib_umem.h
@@ -45,6 +45,9 @@
int page_size;
int writable;
struct list_head chunk_list;
+ struct work_struct work;
+ struct mm_struct *mm;
+ unsigned long diff;
};
struct ib_umem_chunk {
