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[PATCH 2/2] PCI: keystone: Remove the __init macro for the ks_pcie_host_init() callback

Siddharth Vadapalli posted 2 patches 5 months ago
[PATCH 2/2] PCI: keystone: Remove the __init macro for the ks_pcie_host_init() callback
Posted by Siddharth Vadapalli 5 months ago 
The ks_pcie_host_init() callback registered by the driver is invoked by
dw_pcie_host_init(). Since the driver probe is not guaranteed to finish
before the kernel initialization phase, the memory associated with
ks_pcie_host_init() may already be freed by free_initmem().

It is observed in practice that the print associated with free_initmem()
which is:
	"Freeing unused kernel memory: ..."
is displayed before the driver is probed, following which an exception is
triggered when ks_pcie_host_init() is invoked which looks like:

	Unable to handle kernel paging request at virtual address ...
	Mem abort info:
	...
	pc : ks_pcie_host_init+0x0/0x540
	lr : dw_pcie_host_init+0x170/0x498
	...
	ks_pcie_host_init+0x0/0x540 (P)
	ks_pcie_probe+0x728/0x84c
	platform_probe+0x5c/0x98
	really_probe+0xbc/0x29c
	__driver_probe_device+0x78/0x12c
	driver_probe_device+0xd8/0x15c
	...

Fix this by removing the "__init" macro associated with the
ks_pcie_host_init() callback and the ks_pcie_init_id() function that it
internally invokes.

Fixes: 0c4ffcfe1fbc ("PCI: keystone: Add TI Keystone PCIe driver")
Cc: <stable@vger.kernel.org>
Signed-off-by: Siddharth Vadapalli <s-vadapalli@ti.com>
---
 drivers/pci/controller/dwc/pci-keystone.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/controller/dwc/pci-keystone.c b/drivers/pci/controller/dwc/pci-keystone.c
index 21808a9e5158..c6e082dcb3bc 100644
--- a/drivers/pci/controller/dwc/pci-keystone.c
+++ b/drivers/pci/controller/dwc/pci-keystone.c
@@ -799,7 +799,7 @@ static int ks_pcie_fault(unsigned long addr, unsigned int fsr,
 }
 #endif
 
-static int __init ks_pcie_init_id(struct keystone_pcie *ks_pcie)
+static int ks_pcie_init_id(struct keystone_pcie *ks_pcie)
 {
 	int ret;
 	unsigned int id;
@@ -831,7 +831,7 @@ static int __init ks_pcie_init_id(struct keystone_pcie *ks_pcie)
 	return 0;
 }
 
-static int __init ks_pcie_host_init(struct dw_pcie_rp *pp)
+static int ks_pcie_host_init(struct dw_pcie_rp *pp)
 {
 	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
 	struct keystone_pcie *ks_pcie = to_keystone_pcie(pci);
-- 
2.43.0
Re: [PATCH 2/2] PCI: keystone: Remove the __init macro for the ks_pcie_host_init() callback
Posted by Bjorn Helgaas 4 months, 1 week ago 
On Fri, Sep 12, 2025 at 03:37:59PM +0530, Siddharth Vadapalli wrote:
> The ks_pcie_host_init() callback registered by the driver is invoked by
> dw_pcie_host_init(). Since the driver probe is not guaranteed to finish
> before the kernel initialization phase, the memory associated with
> ks_pcie_host_init() may already be freed by free_initmem().
> 
> It is observed in practice that the print associated with free_initmem()
> which is:
> 	"Freeing unused kernel memory: ..."
> is displayed before the driver is probed, following which an exception is
> triggered when ks_pcie_host_init() is invoked which looks like:
> 
> 	Unable to handle kernel paging request at virtual address ...
> 	Mem abort info:
> 	...
> 	pc : ks_pcie_host_init+0x0/0x540
> 	lr : dw_pcie_host_init+0x170/0x498
> 	...
> 	ks_pcie_host_init+0x0/0x540 (P)
> 	ks_pcie_probe+0x728/0x84c
> 	platform_probe+0x5c/0x98
> 	really_probe+0xbc/0x29c
> 	__driver_probe_device+0x78/0x12c
> 	driver_probe_device+0xd8/0x15c
> 	...
> 
> Fix this by removing the "__init" macro associated with the
> ks_pcie_host_init() callback and the ks_pcie_init_id() function that it
> internally invokes.
> 
> Fixes: 0c4ffcfe1fbc ("PCI: keystone: Add TI Keystone PCIe driver")
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Siddharth Vadapalli <s-vadapalli@ti.com>

I dropped this from pci/controller/keystone because of the resulting
section mismatch:

  https://lore.kernel.org/r/202510010726.GPljD7FR-lkp@intel.com

ks_pcie_host_init() calls hook_fault_code(), which is __init, so we
can't make ks_pcie_host_init() non-__init.

Both are bad problems, but there's no point in just swapping one
problem for a different one.

> ---
>  drivers/pci/controller/dwc/pci-keystone.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/pci/controller/dwc/pci-keystone.c b/drivers/pci/controller/dwc/pci-keystone.c
> index 21808a9e5158..c6e082dcb3bc 100644
> --- a/drivers/pci/controller/dwc/pci-keystone.c
> +++ b/drivers/pci/controller/dwc/pci-keystone.c
> @@ -799,7 +799,7 @@ static int ks_pcie_fault(unsigned long addr, unsigned int fsr,
>  }
>  #endif
>  
> -static int __init ks_pcie_init_id(struct keystone_pcie *ks_pcie)
> +static int ks_pcie_init_id(struct keystone_pcie *ks_pcie)
>  {
>  	int ret;
>  	unsigned int id;
> @@ -831,7 +831,7 @@ static int __init ks_pcie_init_id(struct keystone_pcie *ks_pcie)
>  	return 0;
>  }
>  
> -static int __init ks_pcie_host_init(struct dw_pcie_rp *pp)
> +static int ks_pcie_host_init(struct dw_pcie_rp *pp)
>  {
>  	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
>  	struct keystone_pcie *ks_pcie = to_keystone_pcie(pci);
> -- 
> 2.43.0
>
Re: [PATCH 2/2] PCI: keystone: Remove the __init macro for the ks_pcie_host_init() callback
Posted by Siddharth Vadapalli 3 months, 2 weeks ago 
On Thu, 2025-10-02 at 09:36 -0500, Bjorn Helgaas wrote:

Hello Bjorn,

> On Fri, Sep 12, 2025 at 03:37:59PM +0530, Siddharth Vadapalli wrote:
> > The ks_pcie_host_init() callback registered by the driver is invoked by
> > dw_pcie_host_init(). Since the driver probe is not guaranteed to finish
> > before the kernel initialization phase, the memory associated with
> > ks_pcie_host_init() may already be freed by free_initmem().
> > 
> > It is observed in practice that the print associated with free_initmem()
> > which is:
> > 	"Freeing unused kernel memory: ..."
> > is displayed before the driver is probed, following which an exception is
> > triggered when ks_pcie_host_init() is invoked which looks like:
> > 
> > 	Unable to handle kernel paging request at virtual address ...
> > 	Mem abort info:
> > 	...
> > 	pc : ks_pcie_host_init+0x0/0x540
> > 	lr : dw_pcie_host_init+0x170/0x498
> > 	...
> > 	ks_pcie_host_init+0x0/0x540 (P)
> > 	ks_pcie_probe+0x728/0x84c
> > 	platform_probe+0x5c/0x98
> > 	really_probe+0xbc/0x29c
> > 	__driver_probe_device+0x78/0x12c
> > 	driver_probe_device+0xd8/0x15c
> > 	...
> > 
> > Fix this by removing the "__init" macro associated with the
> > ks_pcie_host_init() callback and the ks_pcie_init_id() function that it
> > internally invokes.
> > 
> > Fixes: 0c4ffcfe1fbc ("PCI: keystone: Add TI Keystone PCIe driver")
> > Cc: <stable@vger.kernel.org>
> > Signed-off-by: Siddharth Vadapalli <s-vadapalli@ti.com>
> 
> I dropped this from pci/controller/keystone because of the resulting
> section mismatch:
> 
>   https://lore.kernel.org/r/202510010726.GPljD7FR-lkp@intel.com
> 
> ks_pcie_host_init() calls hook_fault_code(), which is __init, so we
> can't make ks_pcie_host_init() non-__init.
> 
> Both are bad problems, but there's no point in just swapping one
> problem for a different one.

Since this patch is required only for the case where the driver supports
being built as a loadable module, I have reworked on the patch and have
squashed it into patch 4 of the following series:
https://lore.kernel.org/r/20251022095724.997218-5-s-vadapalli@ti.com/
The implementation above ensures that 'hook_fault_code()' is placed within
an '__init' function while the '__init' keywords can safely be removed from
the remaining functions. Please review and let me know.

Regards,
Siddharth.

Patchew 2.1-devel-b67e4c2

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