On Fri, Dec 15, 2017 at 7:01 PM, Yang Shi <yang.s@xxxxxxxxxxxxxxx> wrote: > > > On 12/15/17 4:51 AM, Arnd Bergmann wrote: >> >> When the down_read_trylock() fails, 'vma' has not been initialized >> yet, which gcc now warns about: >> >> mm/khugepaged.c: In function 'khugepaged': >> mm/khugepaged.c:1659:25: error: 'vma' may be used uninitialized in this >> function [-Werror=maybe-uninitialized] > > > Arnd, > > Thanks for catching this. I'm wondering why my test didn't catch it. It > might be because my gcc is old. I'm using gcc 4.8.5 on centos 7. Correct, gcc-4.8 and earlier have too many false-positive warnings with -Wmaybe-uninitialized, so we turn it off on those versions. 4.9 is much better here, but I'd recommend using gcc-6 or gcc-7 when you upgrade, they have a much better set of default warnings besides producing better binary code. See http://git.infradead.org/users/segher/buildall.git for a simple way to build toolchains suitable for building kernels in varying architectures and versions. Arnd -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
