linux-kernel - Re: [PATCH v8 1/5] kasan: support backing vmalloc space with real shadow memory

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Message-ID: <87zhik2b5x.fsf@dja-thinkpad.axtens.net>
Date:   Wed, 02 Oct 2019 11:23:06 +1000
From:   Daniel Axtens <dja@...ens.net>
To:     Uladzislau Rezki <urezki@...il.com>
Cc:     kasan-dev@...glegroups.com, linux-mm@...ck.org, x86@...nel.org,
        aryabinin@...tuozzo.com, glider@...gle.com, luto@...nel.org,
        linux-kernel@...r.kernel.org, mark.rutland@....com,
        dvyukov@...gle.com, christophe.leroy@....fr,
        linuxppc-dev@...ts.ozlabs.org, gor@...ux.ibm.com
Subject: Re: [PATCH v8 1/5] kasan: support backing vmalloc space with real shadow memory

Hi,

>>  	/*
>>  	 * Find a place in the tree where VA potentially will be
>>  	 * inserted, unless it is merged with its sibling/siblings.
>> @@ -741,6 +752,10 @@ merge_or_add_vmap_area(struct vmap_area *va,
>>  		if (sibling->va_end == va->va_start) {
>>  			sibling->va_end = va->va_end;
>>  
>> +			kasan_release_vmalloc(orig_start, orig_end,
>> +					      sibling->va_start,
>> +					      sibling->va_end);
>> +
> The same.

The call to kasan_release_vmalloc() is a static inline no-op if
CONFIG_KASAN_VMALLOC is not defined, which I thought was the preferred
way to do things rather than sprinkling the code with ifdefs?

The complier should be smart enough to eliminate all the
orig_state/orig_end stuff at compile time because it can see that it's
not used, so there's no cost in the binary.

Regards,
Daniel