Commit 1bf66a30 authored by Roland Dreier's avatar Roland Dreier
Browse files

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: default avatarRoland Dreier <rolandd@cisco.com>
parent f7c6a7b5

drivers/infiniband/core/umem.c

+13 −28
Original line number Diff line number Diff line
@@ -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);



	down_write(&work->mm->mmap_sem);

	work->mm->locked_vm -= work->diff;

	up_write(&work->mm->mmap_sem);

	mmput(work->mm);

	kfree(work);

	struct ib_umem *umem = container_of(work, struct ib_umem, 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(&work->work, ib_umem_account);

		work->mm   = mm;

		work->diff = diff;

		INIT_WORK(&umem->work, ib_umem_account);

		umem->mm   = mm;

		umem->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);

include/rdma/ib_umem.h

+3 −0
Original line number Diff line number Diff line
@@ -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 {

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