Messages in this thread | | | From | Qian Cai <> | Subject | Re: [PATCH] fs: fix a data race in i_size_write/i_size_read | Date | Wed, 19 Feb 2020 00:08:40 -0500 |
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> On Feb 18, 2020, at 11:52 PM, Al Viro <viro@zeniv.linux.org.uk> wrote: > > If aligned 64bit stores on 64bit host (note the BITS_PER_LONG ifdefs) end up > being split, the kernel is FUBAR anyway. Details, please - how could that > end up happening?
My understanding is the compiler might decide to split the load into saying two 4-byte loads. Then, we might have,
Load1 Store Load2
where the load value could be a garbage. Also, Marco (the KCSAN maintainer) who knew more of compiler than me mentioned that there is no guarantee that the store will not be split either. Thus, the WRITE_ONCE().
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