Hi,
David Miller wrote: [Mon Sep 30 2013, 12:31:30PM EDT]
>
> This is a respin of the original page_offset and 64-bit page
> table changes with some minor changes and a bug fix:
>
> 1) Bob's ACKs for the first 6 patches added.
>
> 2) Don't use "UL" postfix for shift counts, there is code that
> wants those to be "int", particularly printfs in mm/mm_init.c
> that use the "%d" format specifier for SECTIONS_SHIFT.
>
> 3) Adjust VA_HOLE defines to match what the new 3-level page
> tables can actually provide.
>
> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
This issue I was deflected from by a wind direction change and never returned
to it. I believe you have been here with winfix_trampoline and collapsed
THP thrills. A large userspace stack will encounter a
[ 7603.877098] thp_stack[4583]: segfault at 100758 ip 0000000000100764 (rpc 0000000000100750) sp 000007fefdfff6d1 error 30001 in thp_stack[100000+2000]
.
For THP enabled set to "never", there is no issue. This could be a core
mm issue but not certain.
I'll attempt and find the time to return to this.
thanx,
bob
<<CLIP HERE>>
#define _GNU_SOURCE
#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
static unsigned long getfp()
{
unsigned long fp;
return (unsigned long) &fp;
}
static void stack_grow(unsigned long start, unsigned long size, int bwait)
{
unsigned long fp = getfp();
unsigned long m = start - fp;
unsigned long d;
if (m > size) {
fprintf(stderr, "at limit %lx\n", fp);
if (bwait)
for (d = 0; getfp() && d < (1UL <<30UL); d++);
else
sleep(5);
return;
} else
stack_grow(start, size, bwait);
}
void main(int argc, char **argv)
{
unsigned long start = getfp();
int loop, cnt, rc, bwait;
unsigned long stk_sz;
if (argc != 4)
fprintf(stderr, "%s: stack-mb loop-count bwait\n", argv[0]),
exit(1);
rc = sscanf(argv[1], "%ld", &stk_sz);
if (rc != 1)
fprintf(stderr, "%s: stack-mb bad\n", argv[0]), exit(1);
stk_sz <<= 20UL;
rc = sscanf(argv[2], "%d", &loop);
if (rc != 1)
fprintf(stderr, "%s: loop count bad \n", argv[0]), exit(1);
rc = sscanf(argv[3], "%d", &bwait);
if (rc != 1)
fprintf(stderr, "%s: bwait bad\n", argv[0]), exit(1);
for (cnt = 0; cnt < loop; cnt++)
stack_grow(start, stk_sz, bwait);
}
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