Add a write-only module parameter 'flush' that triggers immediate page reporting. The value specifies a page budget: at least this many pages (at page_reporting_order) will be reported, or all unreported pages if fewer remain. The actual number reported may exceed the budget since each reporting pass processes a full cycle across all zones.
This is helpful when there is a lot of memory freed quickly, and a single cycle may not process all free pages due to internal budget limits. echo 512 > /sys/module/page_reporting/parameters/flush Note: the set callback runs under kernel param_lock, so writing this parameter blocks other built-in parameter writes until the flush loop completes. This is acceptable for a privileged debug/test parameter. Signed-off-by: Michael S. Tsirkin <[email protected]> Assisted-by: Claude:claude-opus-4-6 Assisted-by: cursor-agent:GPT-5.4-xhigh --- mm/page_reporting.c | 54 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 54 insertions(+) diff --git a/mm/page_reporting.c b/mm/page_reporting.c index 691a9e66aa5b..8b278a494ea5 100644 --- a/mm/page_reporting.c +++ b/mm/page_reporting.c @@ -358,6 +358,60 @@ static void page_reporting_process(struct work_struct *work) static DEFINE_MUTEX(page_reporting_mutex); DEFINE_STATIC_KEY_FALSE(page_reporting_enabled); +static int page_reporting_flush_set(const char *val, + const struct kernel_param *kp) +{ + struct page_reporting_dev_info *prdev; + unsigned int budget; + int err; + + err = kstrtouint(val, 0, &budget); + if (err) + return err; + if (!budget) + return 0; + + mutex_lock(&page_reporting_mutex); + prdev = rcu_dereference_protected(pr_dev_info, + lockdep_is_held(&page_reporting_mutex)); + if (prdev) { + unsigned int reported; + bool interrupted = false; + + for (reported = 0; reported < budget; + reported += min(prdev->capacity, budget - reported)) { + /* + * First flush completes any previously scheduled + * reporting work. Then request a new reporting + * cycle and flush again to execute it. + */ + flush_delayed_work(&prdev->work); + __page_reporting_request(prdev); + flush_delayed_work(&prdev->work); + if (atomic_read(&prdev->state) == PAGE_REPORTING_IDLE) + break; + if (signal_pending(current)) { + interrupted = true; + break; + } + } + if (interrupted) { + mutex_unlock(&page_reporting_mutex); + return -EINTR; + } + } + mutex_unlock(&page_reporting_mutex); + return 0; +} + +static const struct kernel_param_ops flush_ops = { + .set = page_reporting_flush_set, + .get = param_get_uint, +}; +static unsigned int page_reporting_flush; +module_param_cb(flush, &flush_ops, &page_reporting_flush, 0200); +MODULE_PARM_DESC(flush, "Report at least N pages at page_reporting_order, or until all reported"); + int page_reporting_register(struct page_reporting_dev_info *prdev) { int err = 0; -- MST
