Re: [PATCH] powerpc/mpic: Fix memory leak of mpic on error paths

[jyoti <jyoti@linux.ibm.com>]

On 2026-09-24 15:05, Amit Machhiwal wrote:
> On 2026/09/24 12:00 PM, Jyoti Gupta wrote:
>> mpic_alloc() allocates struct mpic (and optionally the protected
>> sources bitmap) but does not free them when mpic_setup_error_int() or
>> irq_domain_create_linear() fails, leaking the memory.
>> 
>> Initialise mpic to NULL and free the bitmap and the mpic in the common
>> error path before dropping the device node reference. The register
>> mappings are not released here.
>> 
>> Signed-off-by: Jyoti Gupta <jyoti@linux.ibm.com>
> 
> I see a couple of problems with this patch:
> 
> 1. The patch does not apply.  Both "git apply" and "git am" fail on 
> this patch.
>    I think the context lines around the irq_domain_create_linear() call 
> have
>    tabs converted to spaces, which causes the context match to fail.
> 
>       ❯ git apply
> ./20260924_jyoti_powerpc_mpic_fix_memory_leak_of_mpic_on_error_paths.mbx
> --check --verbose
>       Checking patch arch/powerpc/sysdev/mpic.c...
>       error: while searching for:
>       						 intvec_top,
>       						 &mpic_host_ops, mpic);
> 
>       	/*
>       	 * FIXME: The code leaks the MPIC object and mappings here; this
>       	 * is very unlikely to fail but it ought to be fixed anyways.
>       	 */
>       	if (mpic->irqhost == NULL)
>       		goto err_of_node_put;
> 
> 
>       error: patch failed: arch/powerpc/sysdev/mpic.c:1488
>       error: arch/powerpc/sysdev/mpic.c: patch does not apply
> 
>    Please regenerate with:
> 
>      git format-patch -1
> 
>    and verify with:
> 
>      git apply --check <patch>
> 
>    before resending.
> 

Noted.I will regenerate with git format-patch -1 and verify with git 
apply --check
before resending as v2.

> 2. The mpic_setup_error_int() leak is not actually fixed.  The commit 
> message
>    says both mpic_setup_error_int() and irq_domain_create_linear() 
> failure paths
>    are fixed, but the former still does a bare return NULL:
> 
>      if (fsl_version >= 0x401) {
>          ret = mpic_setup_error_int(mpic, intvec_top - 13);
>          if (ret)
>              return NULL;   /* <-- still leaks mpic and mpic->protected 
> */
>      }
> 
>    This needs to become:
> 
>          if (ret)
>              goto err_of_node_put;
> 
> Thanks,
> Amit
> 

The mpic_setup_error_int() leak is intentionally left to a separate 
patch already under
  review:
"[PATCH] powerpc: Fix missing of_node_put() calls"
That patch converts the return NULL at line 1392 to goto err_of_node_put 
as part of a
broader of_node_put() fix series. This patch focuses only on the 
irq_domain_create_linear()
failure path.

Thanks,
Jyoti