Hi Arnd et al, People started seeing this in today's linux-next... On Tue, Jul 30, 2024 at 4:15 PM Arnd Bergmann <arnd@xxxxxxxxxx> wrote: > On Tue, Jul 30, 2024, at 12:10, Arnd Bergmann wrote: > > On Tue, Jul 30, 2024, at 05:59, Linus Torvalds wrote: > >> On Mon, 29 Jul 2024 at 16:21, Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxx> wrote: > > > > I'm giving this a spin on the randconfig test setup now to see > > if there are some other cases like the bcachefs one. So far I've > > seen one failure, but I can't make sense of it yet: > > > > drivers/gpu/drm/i915/display/intel_backlight.c: In function 'scale': > > include/linux/compiler_types.h:510:45: error: call to > > '__compiletime_assert_905' declared with attribute error: clamp() low > > limit source_min greater than high limit source_max > > include/linux/minmax.h:107:9: note: in expansion of macro > > 'BUILD_BUG_ON_MSG' > > 107 | BUILD_BUG_ON_MSG(statically_true(ulo > uhi), > > \ > > drivers/gpu/drm/i915/display/intel_backlight.c:47:22: note: in > > expansion of macro 'clamp' > > 47 | source_val = clamp(source_val, source_min, source_max); > > > > See https://pastebin.com/raw/yLJ5ZqVw for the x86-64 .config > > that triggered this. > > The above seems to happen only with gcc-13 and gcc-14, but not gcc-12 > and earlier, and it's the only one I've seen with a bit of randconfig > testing on that version. > > There is another one that I see with gcc-8 randconfigs (arm64): > > net/netfilter/ipvs/ip_vs_conn.c: In function 'ip_vs_conn_init': > include/linux/compiler_types.h:510:38: error: call to '__compiletime_assert_1040' declared with attribute error: clamp() low limit min greater than high limit max_avail > 510 | _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__) > | ^ > include/linux/minmax.h:182:28: note: in expansion of macro '__careful_clamp' > 182 | #define clamp(val, lo, hi) __careful_clamp(val, lo, hi) > | ^~~~~~~~~~~~~~~ > net/netfilter/ipvs/ip_vs_conn.c:1498:8: note: in expansion of macro 'clamp' > 1498 | max = clamp(max, min, max_avail); > > I can reproduce this one with gcc-8/9/10, but not gcc-11 > or higher. > > This may be another case of __builtin_constant_p() being > slightly unreliable when a local variable is constant-folded > based on a condition, or with partial inlining. Or perhaps the argument order is wrong, and it should be max = clamp(max_avail, min, max); instead? Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
