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Make user stack limit configurable

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To aid in detecting and debugging stack overflow issues make the
user space stack limit configurable via a new ZFS_STACK_SIZE
environment variable.  The value assigned to ZFS_STACK_SIZE will
be used as the default stack size in bytes.

Because this is mainly useful as a debugging aid in conjunction
with ztest the stack limit is disabled by default.  See the ztest(1)
man page for additional details on using the ZFS_STACK_SIZE
environment variable.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ned Bass <bass6@llnl.gov>
Closes #2743
Issue #2293
This commit is contained in:
Brian Behlendorf
2014-09-25 15:15:45 -07:00
parent cb08f06307
commit aa0ac7caa4
3 changed files with 47 additions and 30 deletions
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lib/libzpool/kernel.c
+24 -24
View File
@@ -146,41 +146,41 @@ zk_thread_create(caddr_t stk, size_t stksize, thread_func_t func, void *arg,
{
kthread_t *kt;
pthread_attr_t attr;
size_t stack;
char *stkstr;
ASSERT3S(state & ~TS_RUN, ==, 0);
ASSERT0(state & ~TS_RUN);
kt = umem_zalloc(sizeof (kthread_t), UMEM_NOFAIL);
kt->t_func = func;
kt->t_arg = arg;
VERIFY0(pthread_attr_init(&attr));
VERIFY0(pthread_attr_setdetachstate(&attr, detachstate));
/*
* The Solaris kernel stack size is 24k for x86/x86_64.
* The Linux kernel stack size is 8k for x86/x86_64.
*
* We reduce the default stack size in userspace, to ensure
* we observe stack overruns in user space as well as in
* kernel space. In practice we can't set the userspace stack
* size to 8k because differences in stack usage between kernel
* space and userspace could lead to spurious stack overflows
* (especially when debugging is enabled). Nevertheless, we try
* to set it to the lowest value that works (currently 8k*4).
* PTHREAD_STACK_MIN is the minimum stack required for a NULL
* procedure in user space and is added in to the stack
* requirements.
* We allow the default stack size in user space to be specified by
* setting the ZFS_STACK_SIZE environment variable. This allows us
* the convenience of observing and debugging stack overruns in
* user space. Explicitly specified stack sizes will be honored.
* The usage of ZFS_STACK_SIZE is discussed further in the
* ENVIRONMENT VARIABLES sections of the ztest(1) man page.
*/
if (stksize == 0) {
stkstr = getenv("ZFS_STACK_SIZE");
stack = PTHREAD_STACK_MIN + MAX(stksize, STACK_SIZE) * 4;
if (stkstr == NULL)
stksize = TS_STACK_MAX;
else
stksize = MAX(atoi(stkstr), TS_STACK_MIN);
}
VERIFY3S(pthread_attr_init(&attr), ==, 0);
VERIFY3S(pthread_attr_setstacksize(&attr, stack), ==, 0);
VERIFY3S(pthread_attr_setguardsize(&attr, PAGESIZE), ==, 0);
VERIFY3S(pthread_attr_setdetachstate(&attr, detachstate), ==, 0);
VERIFY3S(stksize, >, 0);
stksize = P2ROUNDUP(MAX(stksize, TS_STACK_MIN), PAGESIZE);
VERIFY0(pthread_attr_setstacksize(&attr, stksize));
VERIFY0(pthread_attr_setguardsize(&attr, PAGESIZE));
VERIFY3S(pthread_create(&kt->t_tid, &attr, &zk_thread_helper, kt),
==, 0);
VERIFY3S(pthread_attr_destroy(&attr), ==, 0);
VERIFY0(pthread_create(&kt->t_tid, &attr, &zk_thread_helper, kt));
VERIFY0(pthread_attr_destroy(&attr));
return (kt);
}