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s390/mm: Add cond_resched() to cmm_alloc/free_pages()

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Adding/removing large amount of pages at once to/from the CMM balloon
can result in rcu_sched stalls or workqueue lockups, because of busy
looping w/o cond_resched().

Prevent this by adding a cond_resched(). cmm_free_pages() holds a
spin_lock while looping, so it cannot be added directly to the existing
loop. Instead, introduce a wrapper function that operates on maximum 256
pages at once, and add it there.

Signed-off-by: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
This commit is contained in:
Gerald Schaefer 2024-09-02 14:02:19 +02:00 committed by Heiko Carstens
parent 0114009953
commit 131b8db785
1 changed files with 17 additions and 1 deletions
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18
arch/s390/mm/cmm.c
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@ -95,11 +95,12 @@ static long cmm_alloc_pages(long nr, long *counter,
(*counter)++;
spin_unlock(&cmm_lock);
nr--;
cond_resched();
}
return nr;
}
static long cmm_free_pages(long nr, long *counter, struct cmm_page_array **list)
static long __cmm_free_pages(long nr, long *counter, struct cmm_page_array **list)
{
struct cmm_page_array *pa;
unsigned long addr;
@ -123,6 +124,21 @@ static long cmm_free_pages(long nr, long *counter, struct cmm_page_array **list)
return nr;
}
static long cmm_free_pages(long nr, long *counter, struct cmm_page_array **list)
{
long inc = 0;
while (nr) {
inc = min(256L, nr);
nr -= inc;
inc = __cmm_free_pages(inc, counter, list);
if (inc)
break;
cond_resched();
}
return nr + inc;
}
static int cmm_oom_notify(struct notifier_block *self,
unsigned long dummy, void *parm)
{