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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>
This commit is contained in:
Roland Dreier 2007-04-18 20:20:28 -07:00
parent f7c6a7b5d5
commit 1bf66a3042
2 changed files with 15 additions and 27 deletions
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39
drivers/infiniband/core/umem.c
View File

@ -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 @@ out:
}
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 @@ static void ib_umem_account(struct work_struct *_work)
*/
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 @@ void ib_umem_release(struct ib_umem *umem)
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 @@ void ib_umem_release(struct ib_umem *umem)
* 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 @@ void ib_umem_release(struct ib_umem *umem)
current->mm->locked_vm -= diff;
up_write(&mm->mmap_sem);
mmput(mm);
kfree(umem);
}
EXPORT_SYMBOL(ib_umem_release);

3
include/rdma/ib_umem.h
View File

@ -45,6 +45,9 @@ struct ib_umem {
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 {