linux-kernel - [V2][PATCH] rcu: avoid alloc_pages() when recording stack

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Message-Id: <1637018582-10788-1-git-send-email-jun.miao@intel.com>
Date:   Tue, 16 Nov 2021 07:23:02 +0800
From:   Jun Miao <jun.miao@...el.com>
To:     paulmck@...nel.org, urezki@...il.com, elver@...gle.com,
        josh@...htriplett.org, rostedt@...dmis.org,
        mathieu.desnoyers@...icios.com, jiangshanlai@...il.com,
        joel@...lfernandes.org, qiang.zhang1211@...il.com
Cc:     rcu@...r.kernel.org, linux-kernel@...r.kernel.org,
        kasan-dev@...glegroups.com, jianwei.hu@...driver.com,
        Jun Miao <jun.miao@...el.com>
Subject: [V2][PATCH] rcu: avoid alloc_pages() when recording stack

The default kasan_record_aux_stack() calls stack_depot_save() with GFP_NOWAIT,
which in turn can then call alloc_pages(GFP_NOWAIT, ...).  In general, however,
it is not even possible to use either GFP_ATOMIC nor GFP_NOWAIT in certain
non-preemptive contexts/RT kernel including raw_spin_locks (see gfp.h and ab00db216c9c7).
Fix it by instructing stackdepot to not expand stack storage via alloc_pages()
in case it runs out by using kasan_record_aux_stack_noalloc().

Jianwei Hu reported:
BUG: sleeping function called from invalid context at kernel/locking/rtmutex.c:969
in_atomic(): 0, irqs_disabled(): 1, non_block: 0, pid: 15319, name: python3
INFO: lockdep is turned off.
irq event stamp: 0
  hardirqs last  enabled at (0): [<0000000000000000>] 0x0
  hardirqs last disabled at (0): [<ffffffff856c8b13>] copy_process+0xaf3/0x2590
  softirqs last  enabled at (0): [<ffffffff856c8b13>] copy_process+0xaf3/0x2590
  softirqs last disabled at (0): [<0000000000000000>] 0x0
  CPU: 6 PID: 15319 Comm: python3 Tainted: G        W  O 5.15-rc7-preempt-rt #1
  Hardware name: Supermicro SYS-E300-9A-8C/A2SDi-8C-HLN4F, BIOS 1.1b 12/17/2018
  Call Trace:
    show_stack+0x52/0x58
    dump_stack+0xa1/0xd6
    ___might_sleep.cold+0x11c/0x12d
    rt_spin_lock+0x3f/0xc0
    rmqueue+0x100/0x1460
    rmqueue+0x100/0x1460
    mark_usage+0x1a0/0x1a0
    ftrace_graph_ret_addr+0x2a/0xb0
    rmqueue_pcplist.constprop.0+0x6a0/0x6a0
     __kasan_check_read+0x11/0x20
     __zone_watermark_ok+0x114/0x270
     get_page_from_freelist+0x148/0x630
     is_module_text_address+0x32/0xa0
     __alloc_pages_nodemask+0x2f6/0x790
     __alloc_pages_slowpath.constprop.0+0x12d0/0x12d0
     create_prof_cpu_mask+0x30/0x30
     alloc_pages_current+0xb1/0x150
     stack_depot_save+0x39f/0x490
     kasan_save_stack+0x42/0x50
     kasan_save_stack+0x23/0x50
     kasan_record_aux_stack+0xa9/0xc0
     __call_rcu+0xff/0x9c0
     call_rcu+0xe/0x10
     put_object+0x53/0x70
     __delete_object+0x7b/0x90
     kmemleak_free+0x46/0x70
     slab_free_freelist_hook+0xb4/0x160
     kfree+0xe5/0x420
     kfree_const+0x17/0x30
     kobject_cleanup+0xaa/0x230
     kobject_put+0x76/0x90
     netdev_queue_update_kobjects+0x17d/0x1f0
     ... ...
     ksys_write+0xd9/0x180
     __x64_sys_write+0x42/0x50
     do_syscall_64+0x38/0x50
     entry_SYSCALL_64_after_hwframe+0x44/0xa9

Links: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/include/linux/kasan.h?id=7cb3007ce2da27ec02a1a3211941e7fe6875b642
Fixes: 84109ab58590 ("rcu: Record kvfree_call_rcu() call stack for KASAN")
Fixes: 26e760c9a7c8 ("rcu: kasan: record and print call_rcu() call stack")
Reported-by: Jianwei Hu <jianwei.hu@...driver.com>
Reviewed-by: Uladzislau Rezki (Sony) <urezki@...il.com>
Signed-off-by: Jun Miao <jun.miao@...el.com>
---
 kernel/rcu/tree.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index ef8d36f580fc..906b6887622d 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -2982,7 +2982,7 @@ __call_rcu(struct rcu_head *head, rcu_callback_t func)
 	head->func = func;
 	head->next = NULL;
 	local_irq_save(flags);
-	kasan_record_aux_stack(head);
+	kasan_record_aux_stack_noalloc(head);
 	rdp = this_cpu_ptr(&rcu_data);
 
 	/* Add the callback to our list. */
@@ -3547,7 +3547,7 @@ void kvfree_call_rcu(struct rcu_head *head, rcu_callback_t func)
 		return;
 	}
 
-	kasan_record_aux_stack(ptr);
+	kasan_record_aux_stack_noalloc(ptr);
 	success = add_ptr_to_bulk_krc_lock(&krcp, &flags, ptr, !head);
 	if (!success) {
 		run_page_cache_worker(krcp);
-- 
2.32.0