From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ej1-f44.google.com (mail-ej1-f44.google.com [209.85.218.44]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 798E241D217 for ; Mon, 17 Aug 2026 12:43:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.218.44 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786970589; cv=none; b=U9wbLivgkhF0TCtLyyZRjWvpOlY+Rp+skpWBgxuyQK4mF4l4OeKL1zSWPPqU0OjXSdRx8AHbyC9FaEVMeLYRO5WxuzdWHKOpt5UTSahHic96n3a8ebqRJe2kjfaJG5ErwZscXK2ya4w+vHFZ/gJ4m4aanDqKzUZ+SOYKrR0d9mA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786970589; c=relaxed/simple; bh=6W8fGILoEK2GVw5txNRHMOz1yEKoSCNedUwlMSGOu64=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=WMksbI52JozRHoJnT0EZggn2H1hLXGgvr7xrYjF5lCCwiux/Vo6S5AxwKkjNcszr0kWEbsDb0zLmvH9xrJEZzIHxm6U0IgLncWgbxmsev3oPabunsqtyp7pbmeDZx1shZk5ig+N+F4MAnYiDD+lzYkxX91azERbNLq81SZBXgn8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=kH8Tt7Yw; arc=none smtp.client-ip=209.85.218.44 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="kH8Tt7Yw" Received: by mail-ej1-f44.google.com with SMTP id a640c23a62f3a-c2074710751so525439866b.1 for ; Mon, 17 Aug 2026 05:43:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1786970586; x=1787575386; darn=vger.kernel.org; h=cc:to:in-reply-to:references:message-id:content-transfer-encoding :content-type:mime-version:subject:date:from:from:to:cc:subject:date :message-id:reply-to:content-type; bh=sRrI0ZiNFWDC68LZNy9rl9u6YO6/uPndbIK+uC0O4Y4=; b=kH8Tt7Yw+8Hq0FOylz0GFu1x/m5baZwnw8dACgErXKGrvCi01NjUnctYEtFvyubwdo Qv3Rl3vRq4eVQYEhF45B+kwpGQZ+4cNV12K8NFXxEjlyVEo4s9KSE6NzZBw3CqxTYnoz 4Blrv6Ue+witlxvLa/eyS/3MIv91ijTILpUU5/dTD7DrJO2RQ6smA0tlezhEqmH2NVkG VG0NofrVsMio9qw82ARQq0Te6TzxqhOTCD1AVSj4UNAAsnJbyky5bGfuPk8Ifov9Jytg yc5iGhhzNaML1M3X2NGgtxWRH8GY5Dfd+/3gto9q6wX7ERqCHTjxwcbHUP4jusHqXZms tl0g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1786970586; x=1787575386; h=cc:to:in-reply-to:references:message-id:content-transfer-encoding :content-type:mime-version:subject:date:from:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=sRrI0ZiNFWDC68LZNy9rl9u6YO6/uPndbIK+uC0O4Y4=; b=CIxZ/KI6Jv7tQ5j+FYxKoe7n1H1vG629ExnrkfUG4Ylw20pDZnTtdBxdA0kFY6iXFq FcvBGiIuB6sq04TvuJ2tlSfY3jkSRjxswYOoghnaXKkDiOUW6qAJp6auTYr/emQiJLuz 0OZxKqC7/K5Zr2MOkE7R+4QN7Wv6WY+QiUsAqbuKqFDazfIyWpMiefFtClxuQaDeIxRo OdC4x9UXX8zjxpfqSVp/up7aSx5cHJBtZgwx0/G2rbB0Tkq7lOzgEte7S5Ye3Q5KmGic l0r2igR6zHePvqXgu4Uh/TqvQX0kDOxTLhimeRfTtyPeo5DftKsQqC121MOJUvi6Wify rFBQ== X-Forwarded-Encrypted: i=1; AHgh+RrVobjUB+o4SS3TnkHFNo+OhjUpKYO8DWKoZ1EtcGbHux4WaplqXrVoQp4/KIrL2YeY4PqWcESyUtL+Fjs=@vger.kernel.org X-Gm-Message-State: AOJu0Yy2fBvj5ICjAVa4Ia51hWWatWwzuG/QYLTogEA7PHPEcokRP5SB UN3ZYPutteCKYVJ8Lq1JuAYFENxt+cSb8RBEevd+KXCPhXEDA5MS6M0H X-Gm-Gg: AR+sD115CSAqN74l29wUCLLdI5tu6+FNbQ+jz3lqvbwDeNproSWYjCBk9mlxiU16oHa HOAZ4swusjCAYAZcPs5drJ2h3/PefqN/4Pz1o3xr63PcBWag7p+ys7NdZ/m2By6NBQIA7GjkoKC 7eSzf9QxgkZEWOVX/wH2KjASFnOvZH41eLIeKfgUnHtVirOLuHyVxy9h7fatx02dOXCwcgmKf/H FlJ7fMFMXx56T6Yx/vckA8Rt/3q6FrWDCpRBF3IGJi0a4kSYrjudzfqGiScU97cTvtsnKn0iIro JDNRCMOhkyZ6GPzt7T0jxXEW+HkxN6el/XMnbC2NDxAgYN3gRYojaKG2m5W4MRioaaXT7mstizw 7Dj0pPyboJbkq7XiV4bdWGbb4ZuWPU53T3y0evADaS1KsjsxQ8tHg5p1REwK3DQ6wSKLnhKNUWx E4nl06+YBlhzFP5N3H5z+7t4hWAgsPEbLxaFmqL7XOOqNHadFk3A== X-Received: by 2002:a17:907:1609:b0:c16:b87:de64 with SMTP id a640c23a62f3a-c212a1250a6mr1202678666b.15.1786970585499; Mon, 17 Aug 2026 05:43:05 -0700 (PDT) Received: from [127.0.0.1] ([2a09:bac6:3861:1e5a::306:a]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-c217feb99d4sm52626266b.22.2026.08.17.05.43.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 17 Aug 2026 05:43:05 -0700 (PDT) From: Caleb Kan Date: Mon, 17 Aug 2026 13:42:46 +0100 Subject: [PATCH RFC 6/9] mm/slub: materialize trie-backed stack depot traces Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260817-stackdepot-trie-v1-6-53870ca1651b@cloudflare.com> References: <20260817-stackdepot-trie-v1-0-53870ca1651b@cloudflare.com> In-Reply-To: <20260817-stackdepot-trie-v1-0-53870ca1651b@cloudflare.com> To: Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, Vlastimil Babka , Alexander Potapenko , Marco Elver , Dmitry Vyukov , Andrey Konovalov , Oscar Salvador , Caleb Kan , kernel-team@cloudflare.com X-Mailer: b4 0.16.0 From: Caleb Kan SLUB owner tracking stores allocation and free stacks as persistent stack depot handles. Trie-backed handles do not expose contiguous stack-record entries, so __kmem_obj_info() and the alloc_traces and free_traces debugfs files cannot use stack_depot_fetch(). Use stack_depot_fetch_into() with TRACK_ADDRS_COUNT-sized local arrays. This matches the save-side limit. Keep the existing KS_ADDRS_COUNT copy limit and debugfs formatting unchanged for hash-backed handles. Continue to copy or print no frames when the fetch returns zero. Signed-off-by: Caleb Kan --- mm/slub.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index 422bc3e12c02..138c3bc473c9 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -8093,12 +8093,12 @@ void __kmem_obj_info(struct kmem_obj_info *kpp, void *object, struct slab *slab) #ifdef CONFIG_STACKDEPOT { depot_stack_handle_t handle; - unsigned long *entries; + unsigned long entries[TRACK_ADDRS_COUNT]; unsigned int nr_entries; handle = READ_ONCE(trackp->handle); if (handle) { - nr_entries = stack_depot_fetch(handle, &entries); + nr_entries = stack_depot_fetch_into(handle, entries, ARRAY_SIZE(entries)); for (i = 0; i < KS_ADDRS_COUNT && i < nr_entries; i++) kpp->kp_stack[i] = (void *)entries[i]; } @@ -8106,7 +8106,7 @@ void __kmem_obj_info(struct kmem_obj_info *kpp, void *object, struct slab *slab) trackp = get_track(s, objp, TRACK_FREE); handle = READ_ONCE(trackp->handle); if (handle) { - nr_entries = stack_depot_fetch(handle, &entries); + nr_entries = stack_depot_fetch_into(handle, entries, ARRAY_SIZE(entries)); for (i = 0; i < KS_ADDRS_COUNT && i < nr_entries; i++) kpp->kp_free_stack[i] = (void *)entries[i]; } @@ -9815,12 +9815,14 @@ static int slab_debugfs_show(struct seq_file *seq, void *v) #ifdef CONFIG_STACKDEPOT { depot_stack_handle_t handle; - unsigned long *entries; + unsigned long entries[TRACK_ADDRS_COUNT]; unsigned int nr_entries, j; handle = READ_ONCE(l->handle); if (handle) { - nr_entries = stack_depot_fetch(handle, &entries); + nr_entries = + stack_depot_fetch_into(handle, entries, + ARRAY_SIZE(entries)); seq_puts(seq, "\n"); for (j = 0; j < nr_entries; j++) seq_printf(seq, " %pS\n", (void *)entries[j]); -- Git-155)