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![Eric Dumazet](/assets/img/avatar_default.png)
syzbot was able to trigger this warning from new_slab()
/*
* All existing users of the __GFP_NOFAIL are blockable, so warn
* of any new users that actually require GFP_NOWAIT
*/
if (WARN_ON_ONCE(!can_direct_reclaim))
goto fail;
Indeed, we should use __GFP_NOFAIL if direct reclaim is possible.
Hopefully in the future we will be able to use SLAB_NOFAILSLAB
option so that syzbot can benefit from full ref_tracker
even in the presence of memory fault injections.
WARNING: CPU: 0 PID: 13 at mm/page_alloc.c:5081 __alloc_pages_slowpath.constprop.0+0x1b7b/0x20d0 mm/page_alloc.c:5081 mm/page_alloc.c:5081
Modules linked in:
CPU: 0 PID: 13 Comm: ksoftirqd/0 Not tainted 5.16.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:__alloc_pages_slowpath.constprop.0+0x1b7b/0x20d0 mm/page_alloc.c:5081 mm/page_alloc.c:5081
Code: 90 08 00 00 48 81 c7 d8 04 00 00 48 89 f8 48 c1 e8 03 42 80 3c 30 00 0f 84 f0 ea ff ff e8 3d 82 09 00 e9 e6 ea ff ff 4d 89 fd <0f> 0b 48 b8 00 00 00 00 00 fc ff df 48 8b 54 24 30 48 c1 ea 03 80
RSP: 0018:ffffc90000d272b8 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff88813fffc300 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000002 RDI: ffff88813fffc348
RBP: ffff88813fffc300 R08: 00000000000013dc R09: 00000000000013c8
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: ffffc90000d274e8 R14: dffffc0000000000 R15: ffffc90000d274e8
FS: 0000000000000000(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffefe6000f8 CR3: 000000001d21e000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
__alloc_pages+0x412/0x500 mm/page_alloc.c:5382 mm/page_alloc.c:5382
alloc_pages+0x1a7/0x300 mm/mempolicy.c:2191 mm/mempolicy.c:2191
alloc_slab_page mm/slub.c:1793 [inline]
allocate_slab mm/slub.c:1938 [inline]
alloc_slab_page mm/slub.c:1793 [inline] mm/slub.c:1993
allocate_slab mm/slub.c:1938 [inline] mm/slub.c:1993
new_slab+0x349/0x4a0 mm/slub.c:1993 mm/slub.c:1993
___slab_alloc+0x918/0xfe0 mm/slub.c:3022 mm/slub.c:3022
__slab_alloc.constprop.0+0x4d/0xa0 mm/slub.c:3109 mm/slub.c:3109
slab_alloc_node mm/slub.c:3200 [inline]
slab_alloc mm/slub.c:3242 [inline]
slab_alloc_node mm/slub.c:3200 [inline] mm/slub.c:3259
slab_alloc mm/slub.c:3242 [inline] mm/slub.c:3259
kmem_cache_alloc_trace+0x289/0x2c0 mm/slub.c:3259 mm/slub.c:3259
kmalloc include/linux/slab.h:590 [inline]
kzalloc include/linux/slab.h:724 [inline]
kmalloc include/linux/slab.h:590 [inline] lib/ref_tracker.c:74
kzalloc include/linux/slab.h:724 [inline] lib/ref_tracker.c:74
ref_tracker_alloc+0xe1/0x430 lib/ref_tracker.c:74 lib/ref_tracker.c:74
netdev_tracker_alloc include/linux/netdevice.h:3855 [inline]
dev_hold_track include/linux/netdevice.h:3872 [inline]
netdev_tracker_alloc include/linux/netdevice.h:3855 [inline] net/core/dst.c:52
dev_hold_track include/linux/netdevice.h:3872 [inline] net/core/dst.c:52
dst_init+0xe0/0x520 net/core/dst.c:52 net/core/dst.c:52
dst_alloc+0x16b/0x1f0 net/core/dst.c:96 net/core/dst.c:96
rt_dst_alloc+0x73/0x450 net/ipv4/route.c:1614 net/ipv4/route.c:1614
ip_route_input_mc net/ipv4/route.c:1720 [inline]
ip_route_input_mc net/ipv4/route.c:1720 [inline] net/ipv4/route.c:2465
ip_route_input_rcu.part.0+0x4fe/0xcc0 net/ipv4/route.c:2465 net/ipv4/route.c:2465
ip_route_input_rcu net/ipv4/route.c:2420 [inline]
ip_route_input_rcu net/ipv4/route.c:2420 [inline] net/ipv4/route.c:2416
ip_route_input_noref+0x1b8/0x2a0 net/ipv4/route.c:2416 net/ipv4/route.c:2416
ip_rcv_finish_core.constprop.0+0x288/0x1e90 net/ipv4/ip_input.c:354 net/ipv4/ip_input.c:354
ip_rcv_finish+0x135/0x2f0 net/ipv4/ip_input.c:427 net/ipv4/ip_input.c:427
NF_HOOK include/linux/netfilter.h:307 [inline]
NF_HOOK include/linux/netfilter.h:301 [inline]
NF_HOOK include/linux/netfilter.h:307 [inline] net/ipv4/ip_input.c:540
NF_HOOK include/linux/netfilter.h:301 [inline] net/ipv4/ip_input.c:540
ip_rcv+0xaa/0xd0 net/ipv4/ip_input.c:540 net/ipv4/ip_input.c:540
__netif_receive_skb_one_core+0x114/0x180 net/core/dev.c:5350 net/core/dev.c:5350
__netif_receive_skb+0x24/0x1b0 net/core/dev.c:5464 net/core/dev.c:5464
process_backlog+0x2a5/0x6c0 net/core/dev.c:5796 net/core/dev.c:5796
__napi_poll+0xaf/0x440 net/core/dev.c:6364 net/core/dev.c:6364
napi_poll net/core/dev.c:6431 [inline]
napi_poll net/core/dev.c:6431 [inline] net/core/dev.c:6518
net_rx_action+0x801/0xb40 net/core/dev.c:6518 net/core/dev.c:6518
__do_softirq+0x29b/0x9c2 kernel/softirq.c:558 kernel/softirq.c:558
run_ksoftirqd kernel/softirq.c:921 [inline]
run_ksoftirqd kernel/softirq.c:921 [inline] kernel/softirq.c:913
run_ksoftirqd+0x2d/0x60 kernel/softirq.c:913 kernel/softirq.c:913
smpboot_thread_fn+0x645/0x9c0 kernel/smpboot.c:164 kernel/smpboot.c:164
kthread+0x405/0x4f0 kernel/kthread.c:327 kernel/kthread.c:327
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 arch/x86/entry/entry_64.S:295
Fixes: 4e66934eaa
("lib: add reference counting tracking infrastructure")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
143 lines
3.9 KiB
C
143 lines
3.9 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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#include <linux/export.h>
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#include <linux/ref_tracker.h>
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#include <linux/slab.h>
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#include <linux/stacktrace.h>
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#include <linux/stackdepot.h>
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#define REF_TRACKER_STACK_ENTRIES 16
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struct ref_tracker {
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struct list_head head; /* anchor into dir->list or dir->quarantine */
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bool dead;
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depot_stack_handle_t alloc_stack_handle;
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depot_stack_handle_t free_stack_handle;
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};
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void ref_tracker_dir_exit(struct ref_tracker_dir *dir)
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{
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struct ref_tracker *tracker, *n;
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unsigned long flags;
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bool leak = false;
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spin_lock_irqsave(&dir->lock, flags);
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list_for_each_entry_safe(tracker, n, &dir->quarantine, head) {
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list_del(&tracker->head);
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kfree(tracker);
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dir->quarantine_avail++;
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}
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list_for_each_entry_safe(tracker, n, &dir->list, head) {
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pr_err("leaked reference.\n");
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if (tracker->alloc_stack_handle)
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stack_depot_print(tracker->alloc_stack_handle);
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leak = true;
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list_del(&tracker->head);
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kfree(tracker);
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}
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spin_unlock_irqrestore(&dir->lock, flags);
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WARN_ON_ONCE(leak);
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WARN_ON_ONCE(refcount_read(&dir->untracked) != 1);
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}
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EXPORT_SYMBOL(ref_tracker_dir_exit);
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void ref_tracker_dir_print(struct ref_tracker_dir *dir,
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unsigned int display_limit)
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{
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struct ref_tracker *tracker;
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unsigned long flags;
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unsigned int i = 0;
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spin_lock_irqsave(&dir->lock, flags);
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list_for_each_entry(tracker, &dir->list, head) {
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if (i < display_limit) {
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pr_err("leaked reference.\n");
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if (tracker->alloc_stack_handle)
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stack_depot_print(tracker->alloc_stack_handle);
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i++;
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} else {
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break;
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}
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}
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spin_unlock_irqrestore(&dir->lock, flags);
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}
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EXPORT_SYMBOL(ref_tracker_dir_print);
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int ref_tracker_alloc(struct ref_tracker_dir *dir,
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struct ref_tracker **trackerp,
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gfp_t gfp)
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{
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unsigned long entries[REF_TRACKER_STACK_ENTRIES];
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struct ref_tracker *tracker;
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unsigned int nr_entries;
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gfp_t gfp_mask = gfp;
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unsigned long flags;
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if (gfp & __GFP_DIRECT_RECLAIM)
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gfp_mask |= __GFP_NOFAIL;
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*trackerp = tracker = kzalloc(sizeof(*tracker), gfp_mask);
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if (unlikely(!tracker)) {
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pr_err_once("memory allocation failure, unreliable refcount tracker.\n");
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refcount_inc(&dir->untracked);
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return -ENOMEM;
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}
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nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 1);
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nr_entries = filter_irq_stacks(entries, nr_entries);
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tracker->alloc_stack_handle = stack_depot_save(entries, nr_entries, gfp);
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spin_lock_irqsave(&dir->lock, flags);
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list_add(&tracker->head, &dir->list);
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spin_unlock_irqrestore(&dir->lock, flags);
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return 0;
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}
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EXPORT_SYMBOL_GPL(ref_tracker_alloc);
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int ref_tracker_free(struct ref_tracker_dir *dir,
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struct ref_tracker **trackerp)
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{
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unsigned long entries[REF_TRACKER_STACK_ENTRIES];
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struct ref_tracker *tracker = *trackerp;
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depot_stack_handle_t stack_handle;
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unsigned int nr_entries;
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unsigned long flags;
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if (!tracker) {
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refcount_dec(&dir->untracked);
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return -EEXIST;
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}
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nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 1);
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nr_entries = filter_irq_stacks(entries, nr_entries);
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stack_handle = stack_depot_save(entries, nr_entries, GFP_ATOMIC);
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spin_lock_irqsave(&dir->lock, flags);
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if (tracker->dead) {
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pr_err("reference already released.\n");
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if (tracker->alloc_stack_handle) {
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pr_err("allocated in:\n");
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stack_depot_print(tracker->alloc_stack_handle);
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}
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if (tracker->free_stack_handle) {
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pr_err("freed in:\n");
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stack_depot_print(tracker->free_stack_handle);
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}
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spin_unlock_irqrestore(&dir->lock, flags);
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WARN_ON_ONCE(1);
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return -EINVAL;
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}
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tracker->dead = true;
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tracker->free_stack_handle = stack_handle;
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list_move_tail(&tracker->head, &dir->quarantine);
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if (!dir->quarantine_avail) {
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tracker = list_first_entry(&dir->quarantine, struct ref_tracker, head);
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list_del(&tracker->head);
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} else {
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dir->quarantine_avail--;
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tracker = NULL;
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}
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spin_unlock_irqrestore(&dir->lock, flags);
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kfree(tracker);
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return 0;
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}
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EXPORT_SYMBOL_GPL(ref_tracker_free);
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