From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 4AD9E22AE48; Thu, 2 Jul 2026 07:32:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782977537; cv=none; b=pgKzuDTPdpKqIIPJ15D7uaergUaek4AOXqJC2nukOFByonuW638k65OjFSvy/olprVWVB4xZMfzioj4BKjN6ItjHGEWBM8lpzou3lp8WwMwktBfKZXXH9u503xUK9M7Ygud7di4DSWCshs+73OcUdtgYHGUIia8ZOvmn+NrqkL8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782977537; c=relaxed/simple; bh=auLzMwG3Lnq7IbisEmLX7c5+WHEQ3P7wUVPgXjEcLlw=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=fMsU0lnLWB++0W1fKpabGv3LSo1mTd3Bb5p3/tnCXxJFlk6dc2ZuilK3XtNA5hvbRQGfQQIuN5Acrjw4OMbMc1BZz3AsZxCNiWyN4O305iKHeGFMSyEiylHV9YYwrlS2CAoUbYSAFMg/ZFm2jEkHS5cTRE2w1FOQffuOGaySTWk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=MW+Cxy3i; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="MW+Cxy3i" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 709E91F000E9; Thu, 2 Jul 2026 07:32:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1782977535; bh=2X9JgKwdl0p8GFmiN7/WiWwXZjF81If+NXIGu122JaQ=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=MW+Cxy3i7kKl27n3xo/UiBNkar1zcuPifzaQc4/oHmG3ozOFx3XzhBiI30HxM/NDn AdgY1vKY+9+bPi3C6n3Ndgsd+F3hlZEG5fXvpF9tKKcw2aLv+5c8aJXALImk7qSvon +TrqI0OdQFdsviZjihpHIvlOzdwXL7+K5enNi4kz50ntWpUVInHpJliO+JH3GzxaQQ AOiKHvllHPFHVmWTIHLaPWCAKHrvXI5XwUAxskOZgFpRZ6opQjf3WXaxcDVFwRj/4m cDIcqEho3I4oLxFvP1zMiO5ATbeoScRPjoRpXBguxm94o54Co/VlJ1UiXdVvBRqxJD jsEGzvck9t8eA== Message-ID: <82902a84-7e62-496b-b1c0-62bad1be4525@kernel.org> Date: Thu, 2 Jul 2026 09:32:10 +0200 Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC V2 3/3] mm: Replace pgtable entry prints with new format To: Anshuman Khandual , Hugh Dickins Cc: linux-mm@kvack.org, Andy Shevchenko , Rasmus Villemoes , Sergey Senozhatsky , Petr Mladek , Steven Rostedt , Jonathan Corbet , Andrew Morton , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, Lorenzo Stoakes References: <20260610043545.3725735-1-anshuman.khandual@arm.com> <20260610043545.3725735-4-anshuman.khandual@arm.com> <4a416383-62f5-1716-8e04-a2ee1f89a864@google.com> <3afa822d-3cc9-1068-9a10-94a5f2e4d29a@google.com> <90b5cd31-87ed-4ef7-86cc-458b9e06b02d@kernel.org> <5a8e82f3-ed21-48a8-af3c-36a08fd2b0ec@arm.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 7/2/26 06:29, Anshuman Khandual wrote: > > > On 30/06/26 7:06 PM, David Hildenbrand (Arm) wrote: >> On 6/16/26 08:19, Hugh Dickins wrote: >>> >>> Yes, that's what it's for. What we really want is to understand what went >>> wrong: that's too much to ask of a printk, but it can give us a good clue. >>> >>> >>> Page table entry and pmd entry are good enough: higher levels got >>> added at some stage, but they are unlikely to be useful here. >> >> Yes, I added them when we're processing PUD entries we'd also want >> P4D entry + PUD entry. >> >> This is one approach of having the printing be done mostly >> manually, supporting 32, 64 and 128bit pte_val(). As raised by Ryan, >> using local bufs to store the data to not involve printk. >> >> >> I played with printing the byte stream manually, but didn't really like it. >> >> Gave it a quick test and it seems to do its trick. I have the feeling that >> this can be beautified a bit more. >> >> >> From 05af7317b126991a61b0a3d01c2863ce5a578d1b Mon Sep 17 00:00:00 2001 >> From: "David Hildenbrand (Arm)" >> Date: Tue, 30 Jun 2026 15:23:02 +0200 >> Subject: [PATCH] tmp >> >> Signed-off-by: David Hildenbrand (Arm) >> --- >> mm/memory.c | 110 +++++++++++++++++++++++++++++++++++++++++----------- >> 1 file changed, 87 insertions(+), 23 deletions(-) >> >> diff --git a/mm/memory.c b/mm/memory.c >> index ff338c2abe923..ad39cafe110f9 100644 >> --- a/mm/memory.c >> +++ b/mm/memory.c >> @@ -519,9 +519,57 @@ static bool is_bad_page_map_ratelimited(void) >> return false; >> } >> >> +#define PTVAL_STR_MAX (sizeof(u64) * 4 + 1) >> + >> +static void ptval_bytes_to_str(char *buf, size_t buf_size, >> + const void *entry, size_t entry_size) >> +{ >> + if (WARN_ON_ONCE(buf_size < entry_size * 2 + 1)) { >> + snprintf(buf, buf_size, "overflow"); >> + return; >> + } >> + >> + switch (entry_size) { >> + case sizeof(u32): >> + snprintf(buf, buf_size, "%08x", *(const u32 *)entry); >> + break; >> + case sizeof(u64): >> + snprintf(buf, buf_size, "%016llx", >> + (unsigned long long)*(const u64 *)entry); >> + break; >> + case sizeof(u64) * 2: { > > Could this be made sizeof(u128) instead ? But overall this > approach looks good. The would be cleaner. We might have to protect this case by something like #defined(__SIZEOF_INT128__) case sizeof(u128): ... break; #endif default: ... Can you take over this approach and refine it (and address Andy's comments)? I'm not quite happy about the typeof(pud_val(pud)) entry = pud_val(pud); stuff, but I didn't see an easy (less ugly) way to avoid it. Maybe there is one :) -- Cheers, David