I am currently investigating FTBFS of gauche (a scheme interpreter) on
hppa. My knowledge of hppa is quite limited, though. I am not on
this list. Please send Cc: to me.
I have a question of CAS implementation. I assume uni processor
system.
I am looking at:
linux-source-2.6.30/arch/parisc/kernel/syscall.S
----------------
/*
prev = *addr;
if ( prev == old )
*addr = new;
return prev;
*/
[...]
cas_action:
[...]
/* The load and store could fail */
1: ldw 0(%sr3,%r26), %r28
sub,<> %r28, %r25, %r0
2: stw %r24, 0(%sr3,%r26)
----------------
Suppose that <addr> points to copy-on-write memory. At the label 2,
storing data to <addr> will invoke memory trap and it will go to
do_page_fault() to get new memory. In this scenario, is there a
possibility for the process to be scheduled off?
Call chain in question is:
do_page_fault()
->..-> do_wp_page()
->..-> __alloc_pages_internal() with GFP_HIGHUSER_MOVABLE
->..> schedule()
linux/gfp.h has the definition:
#define GFP_HIGHUSER_MOVABLE (__GFP_WAIT | __GFP_IO | __GFP_FS | \
__GFP_HARDWALL | __GFP_HIGHMEM | \
__GFP_MOVABLE)
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