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drm/amdkfd: Reliably prevent reclaim-FS while holding DQM lock

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This is needed to prevent deadlocks when MMU notifiers run in
reclaim-FS context and take the DQM lock for userptr evictions.
Previously this was done by making all memory allocations under
DQM locks GFP_NOIO. This is error prone. Using
memalloc_nofs_save/restore will reliably affect all memory
allocations anywhere in the kernel while the DQM lock is held.

Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Oded Gabbay <oded.gabbay@gmail.com>
This commit is contained in:
Felix Kuehling
2018-07-11 22:32:44 -04:00
committed by Oded Gabbay
parent 0337976f40
commit efeaed4d98
2 changed files with 62 additions and 43 deletions
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20
drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.h
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@@ -26,6 +26,8 @@
#include <linux/rwsem.h>
#include <linux/list.h>
#include <linux/mutex.h>
#include <linux/sched/mm.h>
#include "kfd_priv.h"
#include "kfd_mqd_manager.h"
@@ -173,8 +175,9 @@ struct device_queue_manager {
struct mqd_manager *mqds[KFD_MQD_TYPE_MAX];
struct packet_manager packets;
struct kfd_dev *dev;
struct mutex lock;
struct mutex lock_hidden; /* use dqm_lock/unlock(dqm) */
struct list_head queues;
unsigned int saved_flags;
unsigned int processes_count;
unsigned int queue_count;
unsigned int sdma_queue_count;
@@ -219,4 +222,19 @@ get_sh_mem_bases_nybble_64(struct kfd_process_device *pdd)
return (pdd->lds_base >> 60) & 0x0E;
}
/* The DQM lock can be taken in MMU notifiers. Make sure no reclaim-FS
* happens while holding this lock anywhere to prevent deadlocks when
* an MMU notifier runs in reclaim-FS context.
*/
static inline void dqm_lock(struct device_queue_manager *dqm)
{
mutex_lock(&dqm->lock_hidden);
dqm->saved_flags = memalloc_nofs_save();
}
static inline void dqm_unlock(struct device_queue_manager *dqm)
{
memalloc_nofs_restore(dqm->saved_flags);
mutex_unlock(&dqm->lock_hidden);
}
#endif /* KFD_DEVICE_QUEUE_MANAGER_H_ */