swh:1:snp:77163734605b0ec556b01d897b7bb4a7e30d46b6
Revision bdd804f478a0cc74bf7db8e9f9d5fd379d1b31ca authored by Paul Jackson on 20 May 2006, 22:00:09 UTC, committed by Linus Torvalds on 21 May 2006, 19:59:18 UTC
Fix a couple of infrequently encountered 'sleeping function called from invalid context' in the cpuset hooks in __alloc_pages. Could sleep while interrupts disabled. The routine cpuset_zone_allowed() is called by code in mm/page_alloc.c __alloc_pages() to determine if a zone is allowed in the current tasks cpuset. This routine can sleep, for certain GFP_KERNEL allocations, if the zone is on a memory node not allowed in the current cpuset, but might be allowed in a parent cpuset. But we can't sleep in __alloc_pages() if in interrupt, nor if called for a GFP_ATOMIC request (__GFP_WAIT not set in gfp_flags). The rule was intended to be: Don't call cpuset_zone_allowed() if you can't sleep, unless you pass in the __GFP_HARDWALL flag set in gfp_flag, which disables the code that might scan up ancestor cpusets and sleep. This rule was being violated in a couple of places, due to a bogus change made (by myself, pj) to __alloc_pages() as part of the November 2005 effort to cleanup its logic, and also due to a later fix to constrain which swap daemons were awoken. The bogus change can be seen at: http://linux.derkeiler.com/Mailing-Lists/Kernel/2005-11/4691.html [PATCH 01/05] mm fix __alloc_pages cpuset ALLOC_* flags This was first noticed on a tight memory system, in code that was disabling interrupts and doing allocation requests with __GFP_WAIT not set, which resulted in __might_sleep() writing complaints to the log "Debug: sleeping function called ...", when the code in cpuset_zone_allowed() tried to take the callback_sem cpuset semaphore. We haven't seen a system hang on this 'might_sleep' yet, but we are at decent risk of seeing it fairly soon, especially since the additional cpuset_zone_allowed() check was added, conditioning wakeup_kswapd(), in March 2006. Special thanks to Dave Chinner, for figuring this out, and a tip of the hat to Nick Piggin who warned me of this back in Nov 2005, before I was ready to listen. Signed-off-by: Paul Jackson <pj@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
1 parent 593ee20
Tip revision: a4412fdd49dc011bcc2c0d81ac4cab7457092650 authored by Steven Rostedt (Google) on 21 November 2022, 15:44:03 UTC
error-injection: Add prompt for function error injection
error-injection: Add prompt for function error injection
Tip revision: a4412fd
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crypto | ||
drivers | ||
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include | ||
init | ||
ipc | ||
kernel | ||
lib | ||
mm | ||
net | ||
scripts | ||
security | ||
sound | ||
usr | ||
.gitignore | -rw-r--r-- | 462 bytes |
COPYING | -rw-r--r-- | 18.3 KB |
CREDITS | -rw-r--r-- | 87.4 KB |
Kbuild | -rw-r--r-- | 1.2 KB |
MAINTAINERS | -rw-r--r-- | 68.0 KB |
Makefile | -rw-r--r-- | 43.7 KB |
README | -rw-r--r-- | 16.2 KB |
REPORTING-BUGS | -rw-r--r-- | 3.0 KB |
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