page_pool_track_shutdown01.bt

#!/bin/bpftrace
/*
 * page_pool_track_shutdown01 - Catch when page_pool_destroy see inflight pages
 *
 * NIC driver developers converting their driver to use page_pool, should
 * use this script to verify, they don't leak pages.
 *
 */

BEGIN {
	printf("Tracking page_pool destroy\n");
	printf(" - overlay XDP memory allocator connect+disconnect\n");
	@types[0] = "PAGE_SHARED";
	@types[1] = "PAGE_ORDER0";
	@types[2] = "PAGE_POOL";
	@types[3] = "ZERO_COPY";
}

/* This script depend on kernel change introducing page_pool_destroy().
 * Thus, using it here will cause script to fail, if it is not avail.
 */
kprobe:page_pool_destroy {
	$pp = (uint64)arg0;
	/* On elevated page_pool user_cnt refcnt called multiple times */
	@pp_destroy[$pp] = count();
	// @pp_last_kstack[$pp] = kstack;
}

tracepoint:page_pool:page_pool_release {
	$page_pool = args->pool;
	$inflight  = args->inflight;
	$hold      = args->hold;
	$release   = args->release;

	/* Challenge is that 'mem_id' is unknown to page_pool object.
	 * Thus, identifier is page_pool pointer in map.
	 */
	if ($inflight > 0) {
		$pp = (uint64)$page_pool; /* type-case necessary here */
		@pp_stat_inflight[$pp] = $inflight;
		@pp_stat_hold[$pp]     = $hold;
		@pp_stat_release[$pp]  = $release;

		@pp_inflight_kstack = kstack;

		printf("%s: pp:0x%lX inflight:%d (hold:%d release:%d) (*HIT*)\n",
		       probe, $page_pool, $inflight, $hold, $release);
	} else {
		printf("%s: pp:0x%lX inflight:%d (hold:%d release:%d)\n",
		       probe, $page_pool, $inflight, $hold, $release);
	}
}

tracepoint:xdp:mem_connect {
	$id        = args->mem_id;
	$page_pool = args->allocator;
	$type      = args->mem_type;
	$type_str  = @types[$type];

	// time();  /* Used as event marker */
	printf("%s: type:%s mem.id:%d pp:0x%lX\n",
	       probe, $type_str, $id, $page_pool);

	@active_mem_ids[$id] = nsecs;
}

tracepoint:xdp:mem_disconnect {
	$id        = args->mem_id;
	$page_pool = args->allocator;
	$type      = args->mem_type;
	$type_str  = @types[$type];

	// time(); /* Used as event marker */

	$time_ms = 0;
	if (@active_mem_ids[$id]) {
		$time_ms = (nsecs - @active_mem_ids[$id]) / 1000000;
	}
	printf("%s: type:%s mem.id:%d pp:0x%lX (lived %d ms)\n",
	       probe, $type_str, $id,  $page_pool, $time_ms);

	$pp = (uint64)$page_pool;
	if (@pp_stat_inflight[$pp]) {
		/* An inflight event happened */
		@disconn_kstack[$pp] = kstack;
		printf("%s: INFLIGHT type:%s mem.id:%d pp:0x%lX (lived %d ms)\n",
		       probe, $type_str, $id,  $page_pool, $time_ms);
	}

	delete(@active_mem_ids[$id]);
}

END {
	/* Default bpftrace will print all remaining maps at END */
	clear(@types); /* Avoid printing @types table */
}