| Message ID | 4117363.Ys1FTDH7Wz@wuerfel |
|---|---|
| State | New |
| Headers | show |
On Mon, Jan 18, 2016 at 09:50:26PM +0100, Arnd Bergmann wrote: > A newly added tracepoint in the hugepage code uses a variable in the > error handling that is not initialized at that point: > > include/trace/events/huge_memory.h:81:230: error: 'isolated' may be used uninitialized in this function [-Werror=maybe-uninitialized] > > The result is relatively harmless, as the trace data will in rare > cases contain incorrect data. > > This works around the problem by adding an explicit initialization. > > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > Fixes: 7d2eba0557c1 ("mm: add tracepoint for scanning pages") Reviewed-by: Ebru Akagunduz <ebru.akagunduz@gmail.com> > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index b2db98136af9..bb3b763b1829 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -2320,7 +2320,7 @@ static void collapse_huge_page(struct mm_struct *mm, > pgtable_t pgtable; > struct page *new_page; > spinlock_t *pmd_ptl, *pte_ptl; > - int isolated, result = 0; > + int isolated = 0, result = 0; > unsigned long hstart, hend; > struct mem_cgroup *memcg; > unsigned long mmun_start; /* For mmu_notifiers */ >
On Mon, Jan 18, 2016 at 09:50:26PM +0100, Arnd Bergmann wrote: > A newly added tracepoint in the hugepage code uses a variable in the > error handling that is not initialized at that point: > > include/trace/events/huge_memory.h:81:230: error: 'isolated' may be used uninitialized in this function [-Werror=maybe-uninitialized] > > The result is relatively harmless, as the trace data will in rare > cases contain incorrect data. > > This works around the problem by adding an explicit initialization. > > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > Fixes: 7d2eba0557c1 ("mm: add tracepoint for scanning pages") There's the same patch in mm tree, but it got lost on the way to Linus' tree: https://ozlabs.org/~akpm/mmots/broken-out/mm-make-optimistic-check-for-swapin-readahead-fix.patch Andrew? > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index b2db98136af9..bb3b763b1829 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -2320,7 +2320,7 @@ static void collapse_huge_page(struct mm_struct *mm, > pgtable_t pgtable; > struct page *new_page; > spinlock_t *pmd_ptl, *pte_ptl; > - int isolated, result = 0; > + int isolated = 0, result = 0; > unsigned long hstart, hend; > struct mem_cgroup *memcg; > unsigned long mmun_start; /* For mmu_notifiers */ > -- Kirill A. Shutemov
On Tue, 19 Jan 2016, Kirill A. Shutemov wrote: > > A newly added tracepoint in the hugepage code uses a variable in the > > error handling that is not initialized at that point: > > > > include/trace/events/huge_memory.h:81:230: error: 'isolated' may be used uninitialized in this function [-Werror=maybe-uninitialized] > > > > The result is relatively harmless, as the trace data will in rare > > cases contain incorrect data. > > > > This works around the problem by adding an explicit initialization. > > > > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > > Fixes: 7d2eba0557c1 ("mm: add tracepoint for scanning pages") > > There's the same patch in mm tree, but it got lost on the way to Linus' > tree: > > https://ozlabs.org/~akpm/mmots/broken-out/mm-make-optimistic-check-for-swapin-readahead-fix.patch > > Andrew? > Looks like the patch got the wrong title, mm-make-optimistic-check-for-swapin-readahead-fix.patch, since the subject is "khugepaged: avoid usage of uninitialized variable 'isolated'". Anyway, feel free to add Acked-by: David Rientjes <rientjes@google.com> to either patch. > > > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > > index b2db98136af9..bb3b763b1829 100644 > > --- a/mm/huge_memory.c > > +++ b/mm/huge_memory.c > > @@ -2320,7 +2320,7 @@ static void collapse_huge_page(struct mm_struct *mm, > > pgtable_t pgtable; > > struct page *new_page; > > spinlock_t *pmd_ptl, *pte_ptl; > > - int isolated, result = 0; > > + int isolated = 0, result = 0; > > unsigned long hstart, hend; > > struct mem_cgroup *memcg; > > unsigned long mmun_start; /* For mmu_notifiers */ > >
diff --git a/mm/huge_memory.c b/mm/huge_memory.c index b2db98136af9..bb3b763b1829 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2320,7 +2320,7 @@ static void collapse_huge_page(struct mm_struct *mm, pgtable_t pgtable; struct page *new_page; spinlock_t *pmd_ptl, *pte_ptl; - int isolated, result = 0; + int isolated = 0, result = 0; unsigned long hstart, hend; struct mem_cgroup *memcg; unsigned long mmun_start; /* For mmu_notifiers */
A newly added tracepoint in the hugepage code uses a variable in the error handling that is not initialized at that point: include/trace/events/huge_memory.h:81:230: error: 'isolated' may be used uninitialized in this function [-Werror=maybe-uninitialized] The result is relatively harmless, as the trace data will in rare cases contain incorrect data. This works around the problem by adding an explicit initialization. Signed-off-by: Arnd Bergmann <arnd@arndb.de> Fixes: 7d2eba0557c1 ("mm: add tracepoint for scanning pages")