Andrew Morton wrote:
Nick Piggin <[EMAIL PROTECTED]> wrote:Right now, slab is not really suitable for GFP_ZERO:
#define GFP_LEVEL_MASK (__GFP_WAIT|__GFP_HIGH|__GFP_IO|__GFP_FS| \
- __GFP_COLD|__GFP_NOWARN|__GFP_REPEAT| \
- __GFP_NOFAIL|__GFP_NORETRY|__GFP_NO_GROW|__GFP_COMP)
+ __GFP_COLD|__GFP_NOWARN|__GFP_REPEAT|__GFP_NOFAIL| \
+ __GFP_NORETRY|__GFP_NO_GROW|__GFP_COMP|__GFP_ZERO)
Passing GFP_ZERO into kmem_cache_alloc() is such a bizarre thing to do, perhaps a BUG is the correct response.
I guess it could be argued that the kmem_cache_alloc() callers "knows" that
the ctor will be zeroing out all the objects, but it would seem cleaner to
me to pass the "you should use GFP_ZERO" hint into kmem_cache_create()
rather than kmem_cache_alloc().
- if debug is enabled, then objects are definitively not 0-initialized.
- if a ctor is used for zero initialization, then objects would have to be zeroed before kmem_cache_free: The ctor is only called at object creation, not before object reuse. But memset(,0,) just before free would be a bit silly.
Probably a BUG_ON or WARN_ON should be added into kmem_flagcheck() and into kmem_cache_create().
Should I write a patch? -- Manfred
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