From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id E8788C61DCB for ; Sat, 21 Feb 2026 08:52:47 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 06D7D6B0005; Sat, 21 Feb 2026 03:52:47 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 01B156B0089; Sat, 21 Feb 2026 03:52:46 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E69166B008A; Sat, 21 Feb 2026 03:52:46 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id D4C106B0005 for ; Sat, 21 Feb 2026 03:52:46 -0500 (EST) Received: from smtpin07.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id 6A1461602A3 for ; Sat, 21 Feb 2026 08:52:46 +0000 (UTC) X-FDA: 84467848332.07.59CF49E Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf01.hostedemail.com (Postfix) with ESMTP id CDEBC40009 for ; Sat, 21 Feb 2026 08:52:43 +0000 (UTC) Authentication-Results: imf01.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=NzhTaumS; spf=pass (imf01.hostedemail.com: domain of rppt@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=rppt@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1771663964; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=cRBo0RxqaUPUOOgsI0DNWOWjuQSH2Sw/5vvxe/Ta19w=; b=mEjnInDhBL71iu1gp09WNmrmmN76vyfeXihbhYXfkeYpbS+TtkEmFIdwPL0gVLiMo+78lL UR06H300NaJriGwQYVpahjQBugFGtnqNr6hUsqrn8EHg2eUobsLBkY25Cwry4Y6u5SpiqQ 6IV3qNOZMPt9+bxqmwdoqJgFWcm58qY= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1771663964; a=rsa-sha256; cv=none; b=mnIqAwxrUt0MhkI3feYd2YjExpMT+egM7WsqN9OXJK2LdZLTTrJdp6xUWhjIf9XZ1QllLz OzrzLks9scMOwyaMZKD+FMshNM2f2m3a5hGhoWfzupUw+6gA5vtvjKsm9QvgO4am0rGGyT PNBk2ZP9ZvEqORSGd42XZiTOcRPCRLo= ARC-Authentication-Results: i=1; imf01.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=NzhTaumS; spf=pass (imf01.hostedemail.com: domain of rppt@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=rppt@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id BC92B436F6; Sat, 21 Feb 2026 08:52:42 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0598CC4CEF7; Sat, 21 Feb 2026 08:52:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1771663962; bh=LVxpq5LSIJt0tx8mSURpoTHZALrogPMRrn+LIjNyQno=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=NzhTaumSzl77yt0uRhsXCatJgbXXp8qZkaYbO8lqPNQAJPW4eHHoFRQeN1eN3//NS /0ApTf4179bNiEoojPbuhM3EhTkhsu41x6qQvowOFkRSU8AvQSliW8OOZBEk81W26j RXdLikfGLHewb9Go3BBPS8CjPT32bxZVqP7qbYDgJU5cYGe2vgIeqacYUjWelflctX nRd+6WWblveZ1FKEwfFhEs9nLRy0dZBAMkVO2bsbYhfViXqiqdAICBlJTYeW7Bs0PZ /cwSpyeqAKeHxgepBqvgGmq7/uZSO8L9JISZEV5OgAgDcdQzulc2eFkgUiravYwH6l ZI+xL+VTGXuIQ== Date: Sat, 21 Feb 2026 10:52:36 +0200 From: Mike Rapoport To: "Guilherme G. Piccoli" Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-dev@igalia.com, kernel@gpiccoli.net, Andrew Morton , Steven Rostedt Subject: Re: [PATCH 2/2] mm/memblock: Add reserve_mem debugfs info Message-ID: References: <20260217195816.861684-1-gpiccoli@igalia.com> <20260217195816.861684-3-gpiccoli@igalia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260217195816.861684-3-gpiccoli@igalia.com> X-Rspamd-Queue-Id: CDEBC40009 X-Stat-Signature: coz4scynhr8axyg7cgriidwer6fwah8k X-Rspam-User: X-Rspamd-Server: rspam12 X-HE-Tag: 1771663963-988604 X-HE-Meta: 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 dmTOojbL XUsTc X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Feb 17, 2026 at 04:45:07PM -0300, Guilherme G. Piccoli wrote: > When using the "reserve_mem" parameter, users aim at having an > area that (hopefully) persists across boots, so pstore infrastructure > (like ramoops module) can make use of that to save oops/ftrace logs, > for example. > > There is no easy way to determine if this kernel parameter is properly > set though; the kernel doesn't show information about this memory in > memblock debugfs, neither in /proc/iomem (like unused memory "set" using > "mem=") nor in the kernel log (like the "crashkernel" parameter does). > > Add here a new file under memblock debugfs showing properly set memory > reservations, with name, address and size as passed to "reserve_mem". > > Notice this addition makes the memblock folder *always available* under > debugfs, regardless of ARCH_KEEP_MEMBLOCK and even if there is no > "reserve_mem=" setting in the command-line. > > Cc: Andrew Morton > Cc: Mike Rapoport > Cc: Steven Rostedt > Signed-off-by: Guilherme G. Piccoli > --- > mm/memblock.c | 37 +++++++++++++++++++++++++++++++++++-- > 1 file changed, 35 insertions(+), 2 deletions(-) > > diff --git a/mm/memblock.c b/mm/memblock.c > index 2d2646f7a120..58439de0a59b 100644 > --- a/mm/memblock.c > +++ b/mm/memblock.c > @@ -18,6 +18,10 @@ > #include > #include > > +#ifdef CONFIG_DEBUG_FS > +#include > +#endif No need to ifdef this, a small additional header is not a big deal and it's anyway included in seq_file.h. > + > #ifdef CONFIG_KEXEC_HANDOVER > #include > #include > @@ -2711,7 +2715,7 @@ static int __init reserve_mem(char *p) > } > __setup("reserve_mem=", reserve_mem); > > -#if defined(CONFIG_DEBUG_FS) && defined(CONFIG_ARCH_KEEP_MEMBLOCK) > +#ifdef CONFIG_DEBUG_FS > static const char * const flagname[] = { Flag names only needed when ARCH_KEEP_MEMBLOCK is set ... > [ilog2(MEMBLOCK_HOTPLUG)] = "HOTPLUG", > [ilog2(MEMBLOCK_MIRROR)] = "MIRROR", > @@ -2722,7 +2726,8 @@ static const char * const flagname[] = { > [ilog2(MEMBLOCK_KHO_SCRATCH)] = "KHO_SCRATCH", > }; > > -static int memblock_debug_show(struct seq_file *m, void *private) > +#ifdef CONFIG_ARCH_KEEP_MEMBLOCK ... so this ifdef should go before the flagname declaration. > +static void memblock_debugfs_files(struct seq_file *m) > { > struct memblock_type *type = m->private; > struct memblock_region *reg; > @@ -2754,6 +2759,30 @@ static int memblock_debug_show(struct seq_file *m, void *private) > seq_printf(m, "%s\n", "NONE"); > } > } > +} > +#else > +static void memblock_debugfs_files(struct seq_file *m) {} > +#endif /* CONFIG_ARCH_KEEP_MEMBLOCK */ > + > +static int memblock_debug_show(struct seq_file *m, void *private) > +{ > + if (m->private == &reserved_mem_table[0]) { > + struct reserve_mem_table *map; > + char txtsz[16]; > + > + for (int i = 0; i < reserved_mem_count; i++) { > + map = &reserved_mem_table[i]; > + if (!map->size) > + continue; > + > + memset(txtsz, 0, 16); > + string_get_size((u64)(map->size), 1, STRING_UNITS_2, txtsz, 16); phys_addr_t should be casted automatically to u64 IMO. And please, no magic numbers. > + seq_printf(m, "%s\t\t%pa\t(%s)\n", > + map->name, &map->start, txtsz); Let's not expose the physical address, name and size should be enough to see which reserve_mem allocations succeeded. > + } You can define "reserve_mem" attribute separately, and leave the existing memblock_debug_show() as it was. > + } else > + memblock_debugfs_files(m); > + > return 0; > } > DEFINE_SHOW_ATTRIBUTE(memblock_debug); > @@ -2762,6 +2791,9 @@ static int __init memblock_init_debugfs(void) > { > struct dentry *root = debugfs_create_dir("memblock", NULL); No need to create memblock directory in debugfs if there's nothing to show. Could be something like if (i!(IS_ENABLED(CONFIG_ARCH_KEEP_MEMBLOCK) || reserved_mem_count)) return; root = debugfs_create_dir("memblock", NULL); > + debugfs_create_file("reserve_mem_param", 0444, root, > + &reserved_mem_table[0], &memblock_debug_fops); > +#ifdef CONFIG_ARCH_KEEP_MEMBLOCK > debugfs_create_file("memory", 0444, root, > &memblock.memory, &memblock_debug_fops); > debugfs_create_file("reserved", 0444, root, > @@ -2771,6 +2803,7 @@ static int __init memblock_init_debugfs(void) > &memblock_debug_fops); > #endif > > +#endif /* CONFIG_ARCH_KEEP_MEMBLOCK */ > return 0; > } > __initcall(memblock_init_debugfs); > -- > 2.50.1 > > -- Sincerely yours, Mike.