__get_free_page()

Petr Vandrovec Ing. VTEI (VANDROVE@vc.cvut.cz)
Thu, 16 Jul 1998 11:06:26 MET-1

Hello,
I have problem :-( During reading kernel sources (2.1.109p2) I've found
that there is following code in the __get_free_page:

if (in_interrupt() && (gfp_mask & __GFP_WAIT)) {
static int count = 0;
if (++count < 5) {
printk("gfp called nonatomically .... ");
gfp_mask &= ~__GFP_WAIT;
}
}

I think that we should always do gfp_mask &= ~__GFP_WAIT, not only
for first 4 occurences of this problem, because of try_to_free_pages
tries to lock_kernel() and this does not look too healthy to me.
Yes, I know that this should not happen, but if we checks for this
error, we should do workarounds correctly.
Or am I completely wrong and it is OK to call lock_kernel() (and
try_to_free_pages, swap_out(GFP_WAIT,...)) from interrupt handler?
Thanks,
Petr Vandrovec
vandrove@vc.cvut.cz

P.S.: If it is not OK (2.1.109p2):
--- linux/mm/page_alloc.c.orig Thu Jul 16 10:50:05 1998
+++ linux/mm/page_alloc.c Thu Jul 16 10:51:47 1998
@@ -273,8 +273,8 @@
if (++count < 5) {
printk("gfp called nonatomically from interrupt %p\n",
__builtin_return_address(0));
- gfp_mask &= ~__GFP_WAIT;
}
+ gfp_mask &= ~__GFP_WAIT;
}

for (;;) {


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