Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <5859e93c-23b3-f1f7-9a7c-d2e4c92047eb@gmx.de>
Date:   Thu, 3 Aug 2023 10:02:30 +0200
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101
 Thunderbird/102.13.0
Subject: Re: [PATCH] parisc/mm: preallocate fixmap page tables at init
To:     Mike Rapoport <rppt@kernel.org>
Cc:     Christoph Biedl <linux-kernel.bfrz@manchmal.in-ulm.de>,
        "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>,
        John David Anglin <dave.anglin@bell.net>,
        Vlastimil Babka <vbabka@suse.cz>, linux-parisc@vger.kernel.org,
        linux-kernel@vger.kernel.org
References: <20230803062404.2373480-1-rppt@kernel.org>
Content-Language: en-US
From:   Helge Deller <deller@gmx.de>
In-Reply-To: <20230803062404.2373480-1-rppt@kernel.org>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: quoted-printable
UI-OutboundReport: notjunk:1;M01:P0:cCv/Zue/FhA=;/MUeLeefkbfQvFZTFWjfmbMOO1G
 p2CbgvIztWey6UagEGeWmdDi8ocipXC6oxG54/YLVeEabXaftcFxI9sYqBl+VNpEuzazxFOnU
 xOMooJ8fnz1cyjYIEcP4Pem5amu4nfh5DzWHe9/GkyHDLMA56VB4AWR9h5NC8KNsXK06NGRGb
 ZRItT4iRBCAnQigZiOt9X/CNHwmufMbb4l+5zrB4cmoNcmae4XM2tsvGQFJdtIA5UXAP+RuvL
 VWyR+Hw7Pp6cGyvo8Bg6mq2YvojHMXcJyMq6b0M8Dbx6Wgr/F2TwyJUefvYMv9PZb9RaEAplh
 dWgAOrkoDT1I5J/u9X2dHmJPNVEI4RF59oqZqk/4MXCQtvjkYmMy6R6M3ImUloQsD7vIlz9gO
 dR1zWdhefGNlGBWL4Q3EOILDcc1lDNm+SumVnf825CIlame8E5AIQ59vD1BYLuotUBf7FwisX
 9rYYp0LwvQ5iZVoV0ZJcyulDHRP+avMKFqRjuia6h8rSFQF4eMk9UQavyzjvM+QXbojrHcHes
 zznovfHv/RnY6BLopJrhQ0VwhzKNHz8a+ZEmFzjH+dwr+iK7hKkzmzP7LvGSl/LYsBqoAkiii
 WKa3nmwWMNOvQf8ml+wFta5fRKKq411KWkCFrLUFZLUBSQzQsNUguHInHV2RPghObjT5In6BH
 /H6BA5SzcNmSQ6YUpQROt+KZtFFYclbKLSm+YaiG6IGB/96Yhjwv30m7pUN6zDkrl60+ZmdY2
 5UW0Lqyj5ER2pC7E685X9sNrxO0ceWLJRgZFPWx+++h6DB168IhEtx37hdkzZHgC7cROlhcgX
 qPD2cWU+LmQJmj0kgeNoyd8WOOE72Gy1ItqaxACp1m4noh0XnZwykhp6KpnGhSxCf9hDRKNsl
 U9alRSPEi72/LbP8JDtQ5U6zc7hgNvsKn/xLGmIx4GTHq4JXWMErDgigx/CnFvOzhV/0706oD
 2x0zy6VkAXYyRyvVBpTgNpaEi1E=
Precedence: bulk

On 8/3/23 08:24, Mike Rapoport wrote:
> From: "Mike Rapoport (IBM)" <rppt@kernel.org>
>
> Christoph Biedl reported early OOM on recent kernels:
>
>      swapper: page allocation failure: order:0, mode:0x100(__GFP_ZERO),
> nodemask=3D(null)
>      CPU: 0 PID: 0 Comm: swapper Not tainted 6.3.0-rc4+ #16
>      Hardware name: 9000/785/C3600
>      Backtrace:
>       [<10408594>] show_stack+0x48/0x5c
>       [<10e152d8>] dump_stack_lvl+0x48/0x64
>       [<10e15318>] dump_stack+0x24/0x34
>       [<105cf7f8>] warn_alloc+0x10c/0x1c8
>       [<105d068c>] __alloc_pages+0xbbc/0xcf8
>       [<105d0e4c>] __get_free_pages+0x28/0x78
>       [<105ad10c>] __pte_alloc_kernel+0x30/0x98
>       [<10406934>] set_fixmap+0xec/0xf4
>       [<10411ad4>] patch_map.constprop.0+0xa8/0xdc
>       [<10411bb0>] __patch_text_multiple+0xa8/0x208
>       [<10411d78>] patch_text+0x30/0x48
>       [<1041246c>] arch_jump_label_transform+0x90/0xcc
>       [<1056f734>] jump_label_update+0xd4/0x184
>       [<1056fc9c>] static_key_enable_cpuslocked+0xc0/0x110
>       [<1056fd08>] static_key_enable+0x1c/0x2c
>       [<1011362c>] init_mem_debugging_and_hardening+0xdc/0xf8
>       [<1010141c>] start_kernel+0x5f0/0xa98
>       [<10105da8>] start_parisc+0xb8/0xe4
> ...
>      Kernel Fault: Code=3D15 (Data TLB miss fault) at addr 0f7fe3c0
>      CPU: 0 PID: 0 Comm: swapper Not tainted 6.3.0-rc4+ #16
>      Hardware name: 9000/785/C3600
>
> This happens because patching static key code temporarily maps it via
> fixmap and if it happens before page allocator is initialized set_fixmap=
()
> cannot allocate memory using pte_alloc_kernel().
>
> Make sure that fixmap page tables are preallocated early so that
> pte_offset_kernel() in set_fixmap() never resorts to pte allocation.
>
> Signed-off-by: Mike Rapoport (IBM) <rppt@kernel.org>

Now queued up in parisc for-next tree.

Thanks to Christoph for bisecting and Mike for coming up with this patch!
Helge