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| author | Gerald Schaefer <gerald.schaefer@linux.ibm.com> | 2024-09-02 14:02:19 +0200 |
|---|---|---|
| committer | Heiko Carstens <hca@linux.ibm.com> | 2024-09-05 15:17:23 +0200 |
| commit | 131b8db78558120f58c5dc745ea9655f6b854162 (patch) | |
| tree | 8883d6c5152c82831515d3e58ae522bb09cf5772 /arch/s390 | |
| parent | 0114009953c119021870c42c778b251440a93844 (diff) | |
| download | lwn-131b8db78558120f58c5dc745ea9655f6b854162.tar.gz lwn-131b8db78558120f58c5dc745ea9655f6b854162.zip | |
s390/mm: Add cond_resched() to cmm_alloc/free_pages()
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>
Diffstat (limited to 'arch/s390')
| -rw-r--r-- | arch/s390/mm/cmm.c | 18 |
1 files changed, 17 insertions, 1 deletions
diff --git a/arch/s390/mm/cmm.c b/arch/s390/mm/cmm.c index 75d15bf41d97..d01724a715d0 100644 --- a/arch/s390/mm/cmm.c +++ b/arch/s390/mm/cmm.c @@ -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) { |