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	87773dd56d
	
	
	
		
			
			In debugging an application that receives -ENOMEM from ib_reg_mr(), I
found that ib_umem_get() can fail because the pinned_vm count has
wrapped causing it to always be larger than the lock limit even with
RLIMIT_MEMLOCK set to RLIM_INFINITY.
The wrapping of pinned_vm occurs because the process that calls
ib_reg_mr() will have its mm->pinned_vm count incremented.  Later a
different process with a different mm_struct than the one that
allocated the ib_umem struct ends up releasing it which results in
decrementing the new processes mm->pinned_vm count past zero and
wrapping.
I'm not entirely sure what circumstances cause a different process to
release the ib_umem than the one that allocated it but the kernel
stack trace of the freeing process from my situation looks like the
following:
    Call Trace:
     [<ffffffff814d64b1>] dump_stack+0x19/0x1b
     [<ffffffffa0b522a5>] ib_umem_release+0x1f5/0x200 [ib_core]
     [<ffffffffa0b90681>] mlx4_ib_destroy_qp+0x241/0x440 [mlx4_ib]
     [<ffffffffa0b4d93c>] ib_destroy_qp+0x12c/0x170 [ib_core]
     [<ffffffffa0cc7129>] ib_uverbs_close+0x259/0x4e0 [ib_uverbs]
     [<ffffffff81141cba>] __fput+0xba/0x240
     [<ffffffff81141e4e>] ____fput+0xe/0x10
     [<ffffffff81060894>] task_work_run+0xc4/0xe0
     [<ffffffff810029e5>] do_notify_resume+0x95/0xa0
     [<ffffffff814e3dd0>] int_signal+0x12/0x17
The following patch fixes the issue by storing the pid struct of the
process that calls ib_umem_get() so that ib_umem_release and/or
ib_umem_account() can properly decrement the pinned_vm count of the
correct mm_struct.
Signed-off-by: Shawn Bohrer <sbohrer@rgmadvisors.com>
Reviewed-by: Shachar Raindel <raindel@mellanox.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>
		
	
			
		
			
				
	
	
		
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			79 lines
		
	
	
	
		
			2.5 KiB
			
		
	
	
	
		
			C
		
	
	
	
	
	
| /*
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|  * Copyright (c) 2007 Cisco Systems.  All rights reserved.
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|  *
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|  * This software is available to you under a choice of one of two
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|  * licenses.  You may choose to be licensed under the terms of the GNU
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|  * General Public License (GPL) Version 2, available from the file
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|  * COPYING in the main directory of this source tree, or the
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|  * OpenIB.org BSD license below:
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|  *
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|  *     Redistribution and use in source and binary forms, with or
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|  *     without modification, are permitted provided that the following
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|  *     conditions are met:
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|  *
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|  *      - Redistributions of source code must retain the above
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|  *        copyright notice, this list of conditions and the following
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|  *        disclaimer.
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|  *
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|  *      - Redistributions in binary form must reproduce the above
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|  *        copyright notice, this list of conditions and the following
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|  *        disclaimer in the documentation and/or other materials
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|  *        provided with the distribution.
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|  *
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|  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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|  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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|  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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|  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
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|  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
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|  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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|  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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|  * SOFTWARE.
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|  */
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| 
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| #ifndef IB_UMEM_H
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| #define IB_UMEM_H
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| 
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| #include <linux/list.h>
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| #include <linux/scatterlist.h>
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| #include <linux/workqueue.h>
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| 
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| struct ib_ucontext;
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| 
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| struct ib_umem {
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| 	struct ib_ucontext     *context;
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| 	size_t			length;
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| 	int			offset;
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| 	int			page_size;
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| 	int                     writable;
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| 	int                     hugetlb;
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| 	struct work_struct	work;
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| 	struct pid             *pid;
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| 	struct mm_struct       *mm;
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| 	unsigned long		diff;
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| 	struct sg_table sg_head;
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| 	int             nmap;
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| 	int             npages;
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| };
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| 
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| #ifdef CONFIG_INFINIBAND_USER_MEM
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| 
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| struct ib_umem *ib_umem_get(struct ib_ucontext *context, unsigned long addr,
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| 			    size_t size, int access, int dmasync);
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| void ib_umem_release(struct ib_umem *umem);
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| int ib_umem_page_count(struct ib_umem *umem);
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| 
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| #else /* CONFIG_INFINIBAND_USER_MEM */
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| 
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| #include <linux/err.h>
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| 
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| static inline struct ib_umem *ib_umem_get(struct ib_ucontext *context,
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| 					  unsigned long addr, size_t size,
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| 					  int access, int dmasync) {
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| 	return ERR_PTR(-EINVAL);
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| }
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| static inline void ib_umem_release(struct ib_umem *umem) { }
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| static inline int ib_umem_page_count(struct ib_umem *umem) { return 0; }
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| 
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| #endif /* CONFIG_INFINIBAND_USER_MEM */
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| 
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| #endif /* IB_UMEM_H */
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