Commit a914d8d6 authored by Andrey Konovalov's avatar Andrey Konovalov Committed by Andrew Morton
Browse files

lib/stackdepot: add printk_deferred_enter/exit guards 

Patch series "lib/stackdepot, kasan: fixes for stack eviction series", v3.

A few fixes for the stack depot eviction series ("stackdepot: allow
evicting stack traces").

This patch (of 5):

Stack depot functions can be called from various contexts that do
allocations, including with console locks taken.  At the same time, stack
depot functions might print WARNING's or refcount-related failures.

This can cause a deadlock on console locks.

Add printk_deferred_enter/exit guards to stack depot to avoid this.

Link: https://lkml.kernel.org/r/cover.1703020707.git.andreyknvl@google.com
Link: https://lkml.kernel.org/r/82092f9040d075a161d1264377d51e0bac847e8a.1703020707.git.andreyknvl@google.com


Fixes: 108be8de ("lib/stackdepot: allow users to evict stack traces")
Fixes: cd11016e ("mm, kasan: stackdepot implementation. Enable stackdepot for SLAB")
Signed-off-by: default avatarAndrey Konovalov <andreyknvl@google.com>
Reported-by: default avatarTetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Closes: https://lore.kernel.org/all/000000000000f56750060b9ad216@google.com/


Reviewed-by: default avatarMarco Elver <elver@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 8ab3b097

lib/stackdepot.c

+9 −0
Original line number Diff line number Diff line
@@ -506,12 +506,14 @@ depot_stack_handle_t stack_depot_save_flags(unsigned long *entries, 
	bucket = &stack_table[hash & stack_hash_mask];



	read_lock_irqsave(&pool_rwlock, flags);

	printk_deferred_enter();



	/* Fast path: look the stack trace up without full locking. */

	found = find_stack(bucket, entries, nr_entries, hash);

	if (found) {

		if (depot_flags & STACK_DEPOT_FLAG_GET)

			refcount_inc(&found->count);

		printk_deferred_exit();

		read_unlock_irqrestore(&pool_rwlock, flags);

		goto exit;

	}
@@ -520,6 +522,7 @@ depot_stack_handle_t stack_depot_save_flags(unsigned long *entries, 
	if (new_pool_required)

		need_alloc = true;



	printk_deferred_exit();

	read_unlock_irqrestore(&pool_rwlock, flags);



	/*
@@ -541,6 +544,7 @@ depot_stack_handle_t stack_depot_save_flags(unsigned long *entries, 
	}



	write_lock_irqsave(&pool_rwlock, flags);

	printk_deferred_enter();



	found = find_stack(bucket, entries, nr_entries, hash);

	if (!found) {
@@ -562,6 +566,7 @@ depot_stack_handle_t stack_depot_save_flags(unsigned long *entries, 
			depot_keep_new_pool(&prealloc);

	}



	printk_deferred_exit();

	write_unlock_irqrestore(&pool_rwlock, flags);

exit:

	if (prealloc) {
@@ -600,9 +605,11 @@ unsigned int stack_depot_fetch(depot_stack_handle_t handle, 
		return 0;



	read_lock_irqsave(&pool_rwlock, flags);

	printk_deferred_enter();



	stack = depot_fetch_stack(handle);



	printk_deferred_exit();

	read_unlock_irqrestore(&pool_rwlock, flags);



	*entries = stack->entries;
@@ -619,6 +626,7 @@ void stack_depot_put(depot_stack_handle_t handle) 
		return;



	write_lock_irqsave(&pool_rwlock, flags);

	printk_deferred_enter();



	stack = depot_fetch_stack(handle);

	if (WARN_ON(!stack))
@@ -633,6 +641,7 @@ void stack_depot_put(depot_stack_handle_t handle) 
	}



out:

	printk_deferred_exit();

	write_unlock_irqrestore(&pool_rwlock, flags);

}

EXPORT_SYMBOL_GPL(stack_depot_put);