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![Mikulas Patocka](/assets/img/avatar_default.png)
commit a666e5c05e
upstream.
The system would deadlock when swapping to a dm-crypt device. The reason
is that for each incoming write bio, dm-crypt allocates memory that holds
encrypted data. These excessive allocations exhaust all the memory and the
result is either deadlock or OOM trigger.
This patch limits the number of in-flight swap bios, so that the memory
consumed by dm-crypt is limited. The limit is enforced if the target set
the "limit_swap_bios" variable and if the bio has REQ_SWAP set.
Non-swap bios are not affected becuase taking the semaphore would cause
performance degradation.
This is similar to request-based drivers - they will also block when the
number of requests is over the limit.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
142 lines
3 KiB
C
142 lines
3 KiB
C
/*
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* Internal header file _only_ for device mapper core
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*
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* Copyright (C) 2016 Red Hat, Inc. All rights reserved.
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*
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* This file is released under the LGPL.
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*/
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#ifndef DM_CORE_INTERNAL_H
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#define DM_CORE_INTERNAL_H
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#include <linux/kthread.h>
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#include <linux/ktime.h>
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#include <linux/blk-mq.h>
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#include <trace/events/block.h>
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#include "dm.h"
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#define DM_RESERVED_MAX_IOS 1024
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struct dm_kobject_holder {
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struct kobject kobj;
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struct completion completion;
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};
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/*
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* DM core internal structure that used directly by dm.c and dm-rq.c
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* DM targets must _not_ deference a mapped_device to directly access its members!
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*/
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struct mapped_device {
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struct mutex suspend_lock;
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struct mutex table_devices_lock;
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struct list_head table_devices;
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/*
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* The current mapping (struct dm_table *).
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* Use dm_get_live_table{_fast} or take suspend_lock for
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* dereference.
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*/
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void __rcu *map;
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unsigned long flags;
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/* Protect queue and type against concurrent access. */
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struct mutex type_lock;
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enum dm_queue_mode type;
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int numa_node_id;
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struct request_queue *queue;
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atomic_t holders;
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atomic_t open_count;
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struct dm_target *immutable_target;
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struct target_type *immutable_target_type;
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char name[16];
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struct gendisk *disk;
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struct dax_device *dax_dev;
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/*
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* A list of ios that arrived while we were suspended.
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*/
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struct work_struct work;
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wait_queue_head_t wait;
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spinlock_t deferred_lock;
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struct bio_list deferred;
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void *interface_ptr;
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/*
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* Event handling.
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*/
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wait_queue_head_t eventq;
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atomic_t event_nr;
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atomic_t uevent_seq;
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struct list_head uevent_list;
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spinlock_t uevent_lock; /* Protect access to uevent_list */
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/* the number of internal suspends */
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unsigned internal_suspend_count;
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/*
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* io objects are allocated from here.
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*/
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struct bio_set io_bs;
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struct bio_set bs;
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/*
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* Processing queue (flush)
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*/
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struct workqueue_struct *wq;
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/*
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* freeze/thaw support require holding onto a super block
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*/
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struct super_block *frozen_sb;
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/* forced geometry settings */
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struct hd_geometry geometry;
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/* kobject and completion */
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struct dm_kobject_holder kobj_holder;
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struct block_device *bdev;
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int swap_bios;
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struct semaphore swap_bios_semaphore;
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struct mutex swap_bios_lock;
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struct dm_stats stats;
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/* for blk-mq request-based DM support */
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struct blk_mq_tag_set *tag_set;
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bool init_tio_pdu:1;
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struct srcu_struct io_barrier;
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};
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void disable_discard(struct mapped_device *md);
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void disable_write_same(struct mapped_device *md);
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void disable_write_zeroes(struct mapped_device *md);
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static inline struct completion *dm_get_completion_from_kobject(struct kobject *kobj)
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{
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return &container_of(kobj, struct dm_kobject_holder, kobj)->completion;
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}
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unsigned __dm_get_module_param(unsigned *module_param, unsigned def, unsigned max);
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static inline bool dm_message_test_buffer_overflow(char *result, unsigned maxlen)
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{
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return !maxlen || strlen(result) + 1 >= maxlen;
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}
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extern atomic_t dm_global_event_nr;
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extern wait_queue_head_t dm_global_eventq;
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void dm_issue_global_event(void);
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#endif
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