On 7/12/24 7:31 AM, Byungchul Park wrote: > On Fri, Jul 12, 2024 at 01:44:20PM +0900, Byungchul Park wrote: >> >> What a funny guy... He did neither 1) insisting it's a bug in your code >> nor 3) insisting DEPT is a great tool, but just asking if there's any >> locking rules based on the *different acqusition order* between folio >> lock and i_data_sem that he observed anyway. >> >> I don't think you are a guy who introduces bugs, but the thing is it's >> hard to find a *document* describing locking rules. Anyone could get >> fairly curious about the different acquisition order. It's an open >> source project. You are responsible for appropriate document as well. >> >> I don't understand why you act to DEPT like that by the way. You don't >> have to becasue: >> >> 1. I added the *EXPERIMENTAL* tag in Kconfig as you suggested, which >> will prevent autotesting until it's considered stable. However, >> the report from DEPT can be a good hint to someone. >> >> 2. DEPT can locate code where needs to be documented even if it's not >> a real bug. It could even help better documentation. >> >> DEPT hurts neither code nor performance unless enabling it. enabling means building with CONFIG_DEPT right? >> > If you want to add lock annotations into the struct page or even >> > struct folio, I cordially invite you to try running that by the mm >> > developers, who will probably tell you why that is a terrible idea >> > since it bloats a critical data structure. I doubt anyone will object making struct page larger for a non-production debugging config option, which AFAIU DEPT is, i.e. in the same area as LOCKDEP or KASAN etc... I can see at least KMSAN already adds some fields to struct page already. >> I already said several times. Doesn't consume struct page. > > Sorry for that. I've changed the code so the current version consumes > it by about two words if enabled. I can place it to page_ext as before > if needed. page_ext is useful if you have a debugging feature that can be compiled in but adds no overhead (memory, nor cpu thanks to static keys) unless enabled on boot time, i.e. page_owner... so for DEPT it seems it would be an unnecessary complication. > Byungchul >
