mm: slab: clarify krealloc()'s behavior with __GFP_ZERO

Patch series "slab: provide and use krealloc_array()", v3.

Andy brought to my attention the fact that users allocating an array of
equally sized elements should check if the size multiplication doesn't
overflow.  This is why we have helpers like kmalloc_array().

However we don't have krealloc_array() equivalent and there are many users
who do their own multiplication when calling krealloc() for arrays.

This series provides krealloc_array() and uses it in a couple places.

A separate series will follow adding devm_krealloc_array() which is needed
in the xilinx adc driver.

This patch (of 9):

__GFP_ZERO is ignored by krealloc() (unless we fall-back to kmalloc()
path, in which case it's honored).  Point that out in the kerneldoc.

Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Bartosz Golaszewski <[email protected]>
Cc: Andy Shevchenko <[email protected]>
Cc: Sumit Semwal <[email protected]>
Cc: Gustavo Padovan <[email protected]>
Cc: Christian Knig <[email protected]>
Cc: Mauro Carvalho Chehab <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Tony Luck <[email protected]>
Cc: James Morse <[email protected]>
Cc: Robert Richter <[email protected]>
Cc: Maarten Lankhorst <[email protected]>
Cc: Maxime Ripard <[email protected]>
Cc: Thomas Zimmermann <[email protected]>
Cc: David Airlie <[email protected]>
Cc: Daniel Vetter <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Linus Walleij <[email protected]>
Cc: "Michael S . Tsirkin" <[email protected]>
Cc: Jason Wang <[email protected]>
Cc: Christoph Lameter <[email protected]>
Cc: Pekka Enberg <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Joonsoo Kim <[email protected]>
Cc: Jaroslav Kysela <[email protected]>
Cc: Takashi Iwai <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Daniel Vetter <[email protected]>
Cc: Takashi Iwai <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

1 files changed, 3 insertions, 3 deletions

diff --git a/mm/slab_common.c b/mm/slab_common.c
index 0cd2821b7066..2f2b55c2798e 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -1091,9 +1091,9 @@ static __always_inline void *__do_krealloc(const void *p, size_t new_size,
  * @flags: the type of memory to allocate.
  *
  * The contents of the object pointed to are preserved up to the
- * lesser of the new and old sizes.  If @p is %NULL, krealloc()
- * behaves exactly like kmalloc().  If @new_size is 0 and @p is not a
- * %NULL pointer, the object pointed to is freed.
+ * lesser of the new and old sizes (__GFP_ZERO flag is effectively ignored).
+ * If @p is %NULL, krealloc() behaves exactly like kmalloc().  If @new_size
+ * is 0 and @p is not a %NULL pointer, the object pointed to is freed.
  *
  * Return: pointer to the allocated memory or %NULL in case of error
  */