From nobody Wed Dec 17 08:14:01 2025 Received: from out-182.mta1.migadu.com (out-182.mta1.migadu.com [95.215.58.182]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 151F83D0AB for ; Tue, 19 Dec 2023 21:19:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="elb7wJjm" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1703020797; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=nejB0rN/5EGuA3SQQpabp67CuxIikS5y1NrnTFuMISI=; b=elb7wJjmHVmMnqrahneo3nmWE9hHEyTRVGuiSBGymfQVeOW15J6gqNykSrIgFdw9PIMbZF ta1kf9P/xFptBLk6yUizJYveQGUO6hzXz1/PIciaF5j55mJ3tEib32Ug4OJ35XYc+zlmf1 5OklhsBMYdcTGxBkNXOkqzloDUn2vJw= From: andrey.konovalov@linux.dev To: Andrew Morton Cc: Andrey Konovalov , Marco Elver , Alexander Potapenko , Dmitry Vyukov , Vlastimil Babka , kasan-dev@googlegroups.com, Evgenii Stepanov , Tetsuo Handa , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrey Konovalov Subject: [PATCH v3 mm 1/4] lib/stackdepot: add printk_deferred_enter/exit guards Date: Tue, 19 Dec 2023 22:19:50 +0100 Message-Id: <82092f9040d075a161d1264377d51e0bac847e8a.1703020707.git.andreyknvl@google.com> In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Content-Type: text/plain; charset="utf-8" From: Andrey Konovalov 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. Reported-by: Tetsuo Handa Closes: https://lore.kernel.org/all/000000000000f56750060b9ad216@google.com/ Fixes: 108be8def46e ("lib/stackdepot: allow users to evict stack traces") Fixes: cd11016e5f52 ("mm, kasan: stackdepot implementation. Enable stackdep= ot for SLAB") Reviewed-by: Marco Elver Signed-off-by: Andrey Konovalov --- lib/stackdepot.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/lib/stackdepot.c b/lib/stackdepot.c index 870cce2f4cbd..a0be5d05c7f0 100644 --- a/lib/stackdepot.c +++ b/lib/stackdepot.c @@ -506,12 +506,14 @@ depot_stack_handle_t stack_depot_save_flags(unsigned = long *entries, bucket =3D &stack_table[hash & stack_hash_mask]; =20 read_lock_irqsave(&pool_rwlock, flags); + printk_deferred_enter(); =20 /* Fast path: look the stack trace up without full locking. */ found =3D 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 lo= ng *entries, if (new_pool_required) need_alloc =3D true; =20 + printk_deferred_exit(); read_unlock_irqrestore(&pool_rwlock, flags); =20 /* @@ -541,6 +544,7 @@ depot_stack_handle_t stack_depot_save_flags(unsigned lo= ng *entries, } =20 write_lock_irqsave(&pool_rwlock, flags); + printk_deferred_enter(); =20 found =3D find_stack(bucket, entries, nr_entries, hash); if (!found) { @@ -562,6 +566,7 @@ depot_stack_handle_t stack_depot_save_flags(unsigned lo= ng *entries, depot_keep_new_pool(&prealloc); } =20 + 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 ha= ndle, return 0; =20 read_lock_irqsave(&pool_rwlock, flags); + printk_deferred_enter(); =20 stack =3D depot_fetch_stack(handle); =20 + printk_deferred_exit(); read_unlock_irqrestore(&pool_rwlock, flags); =20 *entries =3D stack->entries; @@ -619,6 +626,7 @@ void stack_depot_put(depot_stack_handle_t handle) return; =20 write_lock_irqsave(&pool_rwlock, flags); + printk_deferred_enter(); =20 stack =3D depot_fetch_stack(handle); if (WARN_ON(!stack)) @@ -633,6 +641,7 @@ void stack_depot_put(depot_stack_handle_t handle) } =20 out: + printk_deferred_exit(); write_unlock_irqrestore(&pool_rwlock, flags); } EXPORT_SYMBOL_GPL(stack_depot_put); --=20 2.25.1