Re: [PATCH v3 4/4] arm: extend pfn_valid to take into account freed memory map alignment

[Mike Rapoport <rppt@kernel.org>]

Hi Guenter,

On Sun, Jul 04, 2021 at 09:22:36PM -0700, Guenter Roeck wrote:
> On Wed, Jun 30, 2021 at 10:12:11AM +0300, Mike Rapoport wrote:
> > From: Mike Rapoport <rppt@linux.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@linux.ibm.com>
> > Tested-by: Kefeng Wang <wangkefeng.wang@huawei.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
...
> [    2.876683] ---[ 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.

I believe this should fix it:

From e2213b7e804daf0d31d47502379916f0542398bb Mon Sep 17 00:00:00 2001
From: Mike Rapoport <rppt@linux.ibm.com>
Date: Mon, 5 Jul 2021 08:43:10 +0300
Subject: [PATCH] arm: ioremap: don't abuse pfn_valid() to check if pfn is in RAM

The semantics of pfn_valid() is to check presence of the memory map for a
PFN and not whether a PFN is in RAM. The memory map may be present for a
hole in the physical memory and if such hole corresponds to an MMIO range,
__arm_ioremap_pfn_caller() will produce a WARN() and fail:

[    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

Use memblock_is_map_memory() instead of pfn_valid() to check if a PFN is in
RAM or not.

Reported-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
---
 arch/arm/mm/ioremap.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/arm/mm/ioremap.c b/arch/arm/mm/ioremap.c
index 000e8210000b..80fb5a4a5c05 100644
--- a/arch/arm/mm/ioremap.c
+++ b/arch/arm/mm/ioremap.c
@@ -27,6 +27,7 @@
 #include <linux/vmalloc.h>
 #include <linux/io.h>
 #include <linux/sizes.h>
+#include <linux/memblock.h>
 
 #include <asm/cp15.h>
 #include <asm/cputype.h>
@@ -284,7 +285,8 @@ static void __iomem * __arm_ioremap_pfn_caller(unsigned long pfn,
 	 * Don't allow RAM to be mapped with mismatched attributes - this
 	 * causes problems with ARMv6+
 	 */
-	if (WARN_ON(pfn_valid(pfn) && mtype != MT_MEMORY_RW))
+	if (WARN_ON(memblock_is_map_memory(PFN_PHYS(pfn)) &&
+		    mtype != MT_MEMORY_RW))
 		return NULL;
 
 	area = get_vm_area_caller(size, VM_IOREMAP, caller);
-- 
2.28.0

-- 
Sincerely yours,
Mike.