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Modify KM_PUSHPAGE to use GFP_NOIO instead of GFP_NOFS 

The resolution of issue #31 made KM_PUSHPAGE imply GFP_NOFS.  This
was done to prevent situations where filesystem operations which are
holding locks enter direct reclaim and attempt to reaquire those
same locks.  This clearly will result in a deadlock.

This works for datasets which are implemented in terms for filesystem
operations.  But unfortunately, swapping to a zvol will encounter
many of the same deadlocks and GFP_NOFS will not prevent this.  As
such, it is appropriate to extend KM_PUSHPAGE to use the broader
GFP_NOIO mask to handle these non-filesystem cases.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue zfsonlinux/zfs#342
Closes #105
This commit is contained in:
Richard Yao 2012-05-01 09:34:39 -04:00 committed by Brian Behlendorf
parent a9a7a01cf5
commit f90096c905
1 changed files with 1 additions and 1 deletions
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2
include/sys/kmem.h
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@ -43,7 +43,7 @@
*/ */
#define KM_SLEEP GFP_KERNEL /* Can sleep, never fails */ #define KM_SLEEP GFP_KERNEL /* Can sleep, never fails */
#define KM_NOSLEEP GFP_ATOMIC /* Can not sleep, may fail */ #define KM_NOSLEEP GFP_ATOMIC /* Can not sleep, may fail */
#define KM_PUSHPAGE (GFP_NOFS | __GFP_HIGH) /* Use reserved memory */ #define KM_PUSHPAGE (GFP_NOIO | __GFP_HIGH) /* Use reserved memory */
#define KM_NODEBUG __GFP_NOWARN /* Suppress warnings */ #define KM_NODEBUG __GFP_NOWARN /* Suppress warnings */
#define KM_FLAGS __GFP_BITS_MASK #define KM_FLAGS __GFP_BITS_MASK
#define KM_VMFLAGS GFP_LEVEL_MASK #define KM_VMFLAGS GFP_LEVEL_MASK