Date:   Sun, 4 Jul 2021 21:22:36 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Mike Rapoport <rppt@...nel.org>
Cc:     linux-arm-kernel@...ts.infradead.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Kefeng Wang <wangkefeng.wang@...wei.com>,
        Mike Rapoport <rppt@...ux.ibm.com>,
        Russell King <linux@...linux.org.uk>,
        Tony Lindgren <tony@...mide.com>, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org
Subject: Re: [PATCH v3 4/4] arm: extend pfn_valid to take into account freed
 memory map alignment

On Wed, Jun 30, 2021 at 10:12:11AM +0300, Mike Rapoport wrote:
> From: Mike Rapoport <rppt@...ux.ibm.com>
> 
> When unused memory map is freed the preserved part of the memory map is
> extended to match pageblock boundaries because lots of core mm
> functionality relies on homogeneity of the memory map within pageblock
> boundaries.
> 
> Since pfn_valid() is used to check whether there is a valid memory map
> entry for a PFN, make it return true also for PFNs that have memory map
> entries even if there is no actual memory populated there.
> 
> Signed-off-by: Mike Rapoport <rppt@...ux.ibm.com>
> Tested-by: Kefeng Wang <wangkefeng.wang@...wei.com>

With this patch in place, the romulus-bmc emulation in qemu gets the
following traceback:

[    2.863406] WARNING: CPU: 0 PID: 1 at arch/arm/mm/ioremap.c:287 __arm_ioremap_pfn_caller+0xf0/0x1dc
[    2.864812] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.13.0-09882-ga180bd1d7e16 #1
[    2.865263] Hardware name: Generic DT based system
[    2.865711] Backtrace: 
[    2.866063] [<80b07e58>] (dump_backtrace) from [<80b080ac>] (show_stack+0x20/0x24)
[    2.866633]  r7:00000009 r6:0000011f r5:60000153 r4:80ddd1c0
[    2.866922] [<80b0808c>] (show_stack) from [<80b18df0>] (dump_stack_lvl+0x58/0x74)
[    2.867117] [<80b18d98>] (dump_stack_lvl) from [<80b18e20>] (dump_stack+0x14/0x1c)
[    2.867309]  r5:80118cac r4:80dc6774
[    2.867404] [<80b18e0c>] (dump_stack) from [<80122fcc>] (__warn+0xe4/0x150)
[    2.867583] [<80122ee8>] (__warn) from [<80b08850>] (warn_slowpath_fmt+0x88/0xc0)
[    2.867774]  r7:0000011f r6:80dc6774 r5:00000000 r4:814c4000
[    2.867917] [<80b087cc>] (warn_slowpath_fmt) from [<80118cac>] (__arm_ioremap_pfn_caller+0xf0/0x1dc)
[    2.868158]  r9:00000001 r8:9ef00000 r7:80e8b0d4 r6:0009ef00 r5:00000000 r4:00100000
[    2.868346] [<80118bbc>] (__arm_ioremap_pfn_caller) from [<80118df8>] (__arm_ioremap_caller+0x60/0x68)
[    2.868581]  r9:9ef00000 r8:821b6dc0 r7:00100000 r6:00000000 r5:815d1010 r4:80118d98
[    2.868761] [<80118d98>] (__arm_ioremap_caller) from [<80118fcc>] (ioremap+0x28/0x30)
[    2.868958] [<80118fa4>] (ioremap) from [<8062871c>] (__devm_ioremap_resource+0x154/0x1c8)
[    2.869169]  r5:815d1010 r4:814c5d2c
[    2.869263] [<806285c8>] (__devm_ioremap_resource) from [<8062899c>] (devm_ioremap_resource+0x14/0x18)
[    2.869495]  r9:9e9f57a0 r8:814c4000 r7:815d1000 r6:815d1010 r5:8177c078 r4:815cf400
[    2.869676] [<80628988>] (devm_ioremap_resource) from [<8091c6e4>] (fsi_master_acf_probe+0x1a8/0x5d8)
[    2.869909] [<8091c53c>] (fsi_master_acf_probe) from [<80723dbc>] (platform_probe+0x68/0xc8)
[    2.870124]  r9:80e9dadc r8:00000000 r7:815d1010 r6:810c1000 r5:815d1010 r4:00000000
[    2.870306] [<80723d54>] (platform_probe) from [<80721208>] (really_probe+0x1cc/0x470)
[    2.870512]  r7:815d1010 r6:810c1000 r5:00000000 r4:815d1010
[    2.870651] [<8072103c>] (really_probe) from [<807215cc>] (__driver_probe_device+0x120/0x1fc)
[    2.870872]  r7:815d1010 r6:810c1000 r5:810c1000 r4:815d1010
[    2.871013] [<807214ac>] (__driver_probe_device) from [<807216e8>] (driver_probe_device+0x40/0xd8)
[    2.871244]  r9:80e9dadc r8:00000000 r7:815d1010 r6:810c1000 r5:812feaa0 r4:812fe994
[    2.871428] [<807216a8>] (driver_probe_device) from [<80721a58>] (__driver_attach+0xa8/0x1d4)
[    2.871647]  r9:80e9dadc r8:00000000 r7:00000000 r6:810c1000 r5:815d1054 r4:815d1010
[    2.871830] [<807219b0>] (__driver_attach) from [<8071ee8c>] (bus_for_each_dev+0x88/0xc8)
[    2.872040]  r7:00000000 r6:814c4000 r5:807219b0 r4:810c1000
[    2.872194] [<8071ee04>] (bus_for_each_dev) from [<80722208>] (driver_attach+0x28/0x30)
[    2.872418]  r7:810a2aa0 r6:00000000 r5:821b6000 r4:810c1000
[    2.872570] [<807221e0>] (driver_attach) from [<8071f80c>] (bus_add_driver+0x114/0x200)
[    2.872788] [<8071f6f8>] (bus_add_driver) from [<80722ec4>] (driver_register+0x98/0x128)
[    2.873011]  r7:81011d0c r6:814c4000 r5:00000000 r4:810c1000
[    2.873167] [<80722e2c>] (driver_register) from [<80725240>] (__platform_driver_register+0x2c/0x34)
[    2.873408]  r5:814dcb80 r4:80f2a764
[    2.873513] [<80725214>] (__platform_driver_register) from [<80f2a784>] (fsi_master_acf_init+0x20/0x28)
[    2.873766] [<80f2a764>] (fsi_master_acf_init) from [<80f014a8>] (do_one_initcall+0x108/0x290)
[    2.874007] [<80f013a0>] (do_one_initcall) from [<80f01840>] (kernel_init_freeable+0x1ac/0x230)
[    2.874248]  r9:80e9dadc r8:80f3987c r7:80f3985c r6:00000007 r5:814dcb80 r4:80f627a4
[    2.874456] [<80f01694>] (kernel_init_freeable) from [<80b19f44>] (kernel_init+0x20/0x138)
[    2.874691]  r10:00000000 r9:00000000 r8:00000000 r7:00000000 r6:00000000 r5:80b19f24
[    2.874894]  r4:00000000
[    2.874977] [<80b19f24>] (kernel_init) from [<80100170>] (ret_from_fork+0x14/0x24)
[    2.875231] Exception stack(0x814c5fb0 to 0x814c5ff8)
[    2.875535] 5fa0:                                     00000000 00000000 00000000 00000000
[    2.875849] 5fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
[    2.876133] 5fe0: 00000000 00000000 00000000 00000000 00000013 00000000
[    2.876363]  r5:80b19f24 r4:00000000
[    2.876683] ---[ end trace b2f74b8536829970 ]---
[    2.876911] fsi-master-acf gpio-fsi: ioremap failed for resource [mem 0x9ef00000-0x9effffff]
[    2.877492] fsi-master-acf gpio-fsi: Error -12 mapping coldfire memory
[    2.877689] fsi-master-acf: probe of gpio-fsi failed with error -12

Reverting it fixes the problem. Also, the ioremap failure is no longer seen
after reverting this patch.

Guenter

---
bisect log:

# bad: [a180bd1d7e16173d965b263c5a536aa40afa2a2a] iov_iter: remove uaccess_kernel() warning from iov_iter_init()
# good: [303392fd5c160822bf778270b28ec5ea50cab2b4] Merge tag 'leds-5.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/pavel/linux-leds
git bisect start 'HEAD' '303392fd5c16'
# good: [2bb919b62f6e5959552a90a399d09d683afa3d1d] Merge tag 's390-5.14-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux
git bisect good 2bb919b62f6e5959552a90a399d09d683afa3d1d
# good: [5390473ec1697b71af0e9d63ef7aaa7ecd27e2c9] rcu: Don't penalize priority boosting when there is nothing to boost
git bisect good 5390473ec1697b71af0e9d63ef7aaa7ecd27e2c9
# good: [641faf1b9064c270a476a424e60063bb05df3ee9] Merge branches 'bitmaprange.2021.05.10c', 'doc.2021.05.10c', 'fixes.2021.05.13a', 'kvfree_rcu.2021.05.10c', 'mmdumpobj.2021.05.10c', 'nocb.2021.05.12a', 'srcu.2021.05.12a', 'tasks.2021.05.18a' and 'torture.2021.05.10c' into HEAD
git bisect good 641faf1b9064c270a476a424e60063bb05df3ee9
# good: [b930226f3db870cfb683c2744aeb0d29deb4cddc] kcsan: Document "value changed" line
git bisect good b930226f3db870cfb683c2744aeb0d29deb4cddc
# bad: [a412897fb546fbb291095be576165ce757eff70b] Merge tag 'memblock-v5.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rppt/memblock
git bisect bad a412897fb546fbb291095be576165ce757eff70b
# good: [f921f53e089a12a192808ac4319f28727b35dc0f] memblock: align freed memory map on pageblock boundaries with SPARSEMEM
git bisect good f921f53e089a12a192808ac4319f28727b35dc0f
# bad: [a4d5613c4dc6d413e0733e37db9d116a2a36b9f3] arm: extend pfn_valid to take into account freed memory map alignment
git bisect bad a4d5613c4dc6d413e0733e37db9d116a2a36b9f3
# good: [023accf5cdc1e504a9b04187ec23ff156fe53d90] memblock: ensure there is no overflow in memblock_overlaps_region()
git bisect good 023accf5cdc1e504a9b04187ec23ff156fe53d90
# first bad commit: [a4d5613c4dc6d413e0733e37db9d116a2a36b9f3] arm: extend pfn_valid to take into account freed memory map alignment

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