Messages in this thread Patch in this message | | | Subject | Re: [PATCH -next] x86/mm/pat: silence a data race in cpa_4k_install | From | Qian Cai <> | Date | Tue, 21 Jan 2020 15:21:35 -0500 |
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> On Jan 21, 2020, at 10:45 AM, Borislav Petkov <bp@alien8.de> wrote: > > On Tue, Jan 21, 2020 at 04:36:49PM +0100, Marco Elver wrote: >> Isn't the intent "x86/mm/pat: Mark intentional data race" ? The fact >> that KCSAN no longer shows the warning is a side-effect. At least >> that's how I see it. > > Perhaps because you've been dealing with KCSAN for so long. :-) > > The main angle here, IMO, is that this "fix" is being done solely for > KCSAN. Or is there another reason to "fix" intentional data races? At > least I don't see one. And the text says > > "This will generate a lot of noise on a debug kernel with > debug_pagealloc with KCSAN enabled which could render the system > unusable." > > So yes, I think it should say something about making KCSAN happy. > > Oh, and while at it I'd prefer it if it did the __no_kcsan function > annotation instead of the data_race() thing.
Actually "__no_kcsan" does not work because I have CONFIG_OPTIMIZE_INLINING=y (GCC 8.3.1) here, so it has to be,
diff --git a/arch/x86/mm/pat/set_memory.c b/arch/x86/mm/pat/set_memory.c index 20823392f4f2..fabbf8a33b7f 100644 --- a/arch/x86/mm/pat/set_memory.c +++ b/arch/x86/mm/pat/set_memory.c @@ -126,7 +126,7 @@ static inline void cpa_inc_2m_checked(void) cpa_2m_checked++; } -static inline void cpa_inc_4k_install(void) +static inline void __no_kcsan_or_inline cpa_inc_4k_install(void) { cpa_4k_install++; } Are you fine with it or data_race() looks better?
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