On 6/16/20 2:53 PM, Joe Perches wrote:

On Mon, 2020-06-15 at 21:57 -0400, Waiman Long wrote:

quoted

  v4:
   - Break out the memzero_explicit() change as suggested by Dan Carpenter
     so that it can be backported to stable.
   - Drop the "crypto: Remove unnecessary memzero_explicit()" patch for
     now as there can be a bit more discussion on what is best. It will be
     introduced as a separate patch later on after this one is merged.

To this larger audience and last week without reply:
https://lore.kernel.org/lkml/573b3fbd5927c643920e1364230c296b23e7584d.camel@perches.com/ (local)

Are there _any_ fastpath uses of kfree or vfree?

Many patches have been posted recently to fix mispairings
of specific types of alloc and free functions.

To eliminate these mispairings at a runtime cost of four
comparisons, should the kfree/vfree/kvfree/kfree_const
functions be consolidated into a single kfree?

Something like the below:

    void kfree(const void *addr)
    {
    	if (is_kernel_rodata((unsigned long)addr))
    		return;

    	if (is_vmalloc_addr(addr))
    		_vfree(addr);
    	else
    		_kfree(addr);
    }

    #define kvfree		kfree
    #define vfree		kfree
    #define kfree_const	kfree

How about adding CONFIG_DEBUG_VM code to check for invalid address 
ranges in kfree() and vfree()? By doing this, we can catch unmatched 
pairing in debug mode, but won't have the overhead when debug mode is off.

Thought?

Cheers,
Longman