Messages in this thread | | | Subject | Re: [PATCH v2 01/17] powerpc/mm: Don't BUG() in hugepd_page() | From | Christophe Leroy <> | Date | Thu, 2 May 2019 14:11:16 +0200 |
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Le 02/05/2019 à 14:02, Michael Ellerman a écrit : > Christophe Leroy <christophe.leroy@c-s.fr> writes: >> Use VM_BUG_ON() instead of BUG_ON(), as those BUG_ON() >> are not there to catch runtime errors but to catch errors >> during development cycle only. > > I've dropped this one and the next, because I don't like VM_BUG_ON(). > > Why not? Because it's contradictory. It's a condition that's so > important that we should BUG, but only if the kernel has been built > specially for debugging. > > I don't really buy the development cycle distinction, it's not like we > have a rigorous test suite that we run and then we declare everything's > gold and ship a product. We often don't find bugs until they're hit in > the wild. > > For example the recent corruption Joel discovered with STRICT_KERNEL_RWX > could have been caught by a BUG_ON() to check we weren't patching kernel > text in radix__change_memory_range(), but he wouldn't have been using > CONFIG_DEBUG_VM. (See 8adddf349fda) > > I know Aneesh disagrees with me on this, so maybe you two can convince > me otherwise. >
I have no strong oppinion about this. In v1, I replaced them with a WARN_ON(), and Aneesh suggested to go with VM_BUG_ON() instead.
My main purpose was to reduce the amount of BUG/BUG_ON and I thought those were good candidates, but if you prefer keeping the BUG(), that's ok for me. Or maybe you prefered v1 alternatives (series at https://patchwork.ozlabs.org/project/linuxppc-dev/list/?series=98170) ?
Christophe
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