Am Samstag, 18. Juni 2022, 17:14:34 CEST schrieb John David Anglin: > Anonymous pages are allocated with the shared mappings colouring, > SHM_COLOUR. Since the alias boundary on machines with PA8800 and > PA8900 processors is unknown, flush_user_cache_page() might not > flush all mappings of a shared anonymous page. Flushing the whole > data cache flushes all mappings. > > This won't fix all coherency issues with shared mappings but it > seems to work well in practice. I haven't seen any random memory > faults in almost a month on a rp3440 running as a debian buildd > machine. > > There is a small preformance hit. Is there a limit we can limit this to the given CPU types? And given that this seems to be a best effort workaround I would suggest adding a comment in the code as explaining why this happens, otherwise someone looking at the code in 3 years may not get the point of it and a quick test will just show "oh, it works without that". Eike
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