Re: [Xen-devel] [PATCH v2 19/21] treewide: add checks for the return value of memblock_alloc*()

[Mike Rapoport <rppt@xxxxxxxxxxxxx>]

On Thu, Jan 31, 2019 at 07:07:46AM +0100, Christophe Leroy wrote:
> 
> 
> Le 21/01/2019 à 09:04, Mike Rapoport a écrit :
> >Add check for the return value of memblock_alloc*() functions and call
> >panic() in case of error.
> >The panic message repeats the one used by panicing memblock allocators with
> >adjustment of parameters to include only relevant ones.
> >
> >The replacement was mostly automated with semantic patches like the one
> >below with manual massaging of format strings.
> >
> >@@
> >expression ptr, size, align;
> >@@
> >ptr = memblock_alloc(size, align);
> >+ if (!ptr)
> >+    panic("%s: Failed to allocate %lu bytes align=0x%lx\n", __func__,
> >size, align);
> >
> >Signed-off-by: Mike Rapoport <rppt@xxxxxxxxxxxxx>
> >Reviewed-by: Guo Ren <ren_guo@xxxxxxxxx>             # c-sky
> >Acked-by: Paul Burton <paul.burton@xxxxxxxx>      # MIPS
> >Acked-by: Heiko Carstens <heiko.carstens@xxxxxxxxxx> # s390
> >Reviewed-by: Juergen Gross <jgross@xxxxxxxx>         # Xen
> >---
> 
> [...]
> 
> >diff --git a/mm/sparse.c b/mm/sparse.c
> >index 7ea5dc6..ad94242 100644
> >--- a/mm/sparse.c
> >+++ b/mm/sparse.c
> 
> [...]
> 
> >@@ -425,6 +436,10 @@ static void __init sparse_buffer_init(unsigned long 
> >size, int nid)
> >             memblock_alloc_try_nid_raw(size, PAGE_SIZE,
> >                                             __pa(MAX_DMA_ADDRESS),
> >                                             MEMBLOCK_ALLOC_ACCESSIBLE, nid);
> >+    if (!sparsemap_buf)
> >+            panic("%s: Failed to allocate %lu bytes align=0x%lx nid=%d 
> >from=%lx\n",
> >+                  __func__, size, PAGE_SIZE, nid, __pa(MAX_DMA_ADDRESS));
> >+
> 
> memblock_alloc_try_nid_raw() does not panic (help explicitly says: Does not
> zero allocated memory, does not panic if request cannot be satisfied.).

"Does not panic" does not mean it always succeeds.
 
> Stephen Rothwell reports a boot failure due to this change.

Please see my reply on that thread.

> Christophe
> 
> >     sparsemap_buf_end = sparsemap_buf + size;
> >  }
> >
> 

-- 
Sincerely yours,
Mike.


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