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Date: Tue, 2 Jan 2024 18:36:15 -0800 (PST)
From: David Rientjes <rientjes@google.com>
To: Gang Li <gang.li@linux.dev>
cc: David Hildenbrand <david@redhat.com>, 
    Mike Kravetz <mike.kravetz@oracle.com>, 
    Muchun Song <muchun.song@linux.dev>, 
    Andrew Morton <akpm@linux-foundation.org>, 
    Tim Chen <tim.c.chen@linux.intel.com>, linux-mm@kvack.org, 
    linux-kernel@vger.kernel.org, ligang.bdlg@bytedance.com
Subject: Re: [PATCH v3 4/7] hugetlb: pass *next_nid_to_alloc directly to
 for_each_node_mask_to_alloc
In-Reply-To: <958bf051-e776-4cbf-ae3c-76ee82d55bcc@linux.dev>
Message-ID: <d6b8518b-9686-5766-d906-6b35edab2583@google.com>
References: <20240102131249.76622-1-gang.li@linux.dev> <20240102131249.76622-5-gang.li@linux.dev> <19b08bb8-1fbd-557b-2684-5c29c5c783e6@google.com> <958bf051-e776-4cbf-ae3c-76ee82d55bcc@linux.dev>
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On Wed, 3 Jan 2024, Gang Li wrote:

> On 2024/1/3 09:32, David Rientjes wrote:
> > Same error as v2:
> > 
> > mm/hugetlb.c:3315:53: warning: variable 'node' is used uninitialized
> > whenever '&&' condition is false [-Wsometimes-uninitialized]
> >          for_each_node_mask_to_alloc(&h->next_nid_to_alloc, nr_nodes, node,
> > &node_states[N_MEMORY]) {
> >          ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > mm/hugetlb.c:1501:3: note: expanded from macro 'for_each_node_mask_to_alloc'
> >                  nr_nodes > 0 &&                                         \
> >                  ^~~~~~~~~~~~
> > mm/hugetlb.c:3342:38: note: uninitialized use occurs here
> >          list_add(&m->list, &huge_boot_pages[node]);
> >                                              ^~~~
> > mm/hugetlb.c:3315:53: note: remove the '&&' if its condition is always true
> >          for_each_node_mask_to_alloc(&h->next_nid_to_alloc, nr_nodes, node,
> > &node_states[N_MEMORY]) {
> >                                                             ^
> > mm/hugetlb.c:3310:7: warning: variable 'node' is used uninitialized whenever
> > 'if' condition is false [-Wsometimes-uninitialized]
> >                  if (!m)
> >                      ^~
> > mm/hugetlb.c:3342:38: note: uninitialized use occurs here
> >          list_add(&m->list, &huge_boot_pages[node]);
> >                                              ^~~~
> > mm/hugetlb.c:3310:3: note: remove the 'if' if its condition is always true
> >                  if (!m)
> >                  ^~~~~~~
> > mm/hugetlb.c:3304:20: note: initialize the variable 'node' to silence this
> > warning
> >          int nr_nodes, node;
> >                            ^
> >                             = 0
> > 2 warnings generated.
> > 
> 
> How did you get those warnings? I got nothing in my compilation.
> 

I'm using clang.

You spotted the issue in your earlier reply about the potentially 
uninitialized use of "node" when adding to the list.