On Mon, 18 Jul 2022 16:26:25 +0200 Marco Elver <elver@xxxxxxxxxx> wrote: > On Sat, 16 Jul 2022 at 20:43, Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> wrote: > [...] > > > - This patch has been accused of crashing the kernel: > > > > > > https://lkml.kernel.org/r/YsFeUHkrFTQ7T51Q@xsang-OptiPlex-9020 > > > > > > Do we think that report is bogus? > > > > I think all of this is highly architecture-specific... > > The report can be reproduced on i386 with CONFIG_X86_PAE=y. But e.g. > mm/memblock.c:memblock_free() is also guilty of using __pa() on > previously memblock_alloc()'d addresses. Looking at the phys addr > before memblock_alloc() does virt_to_phys(), the result of __pa() > looks correct even on PAE, at least for the purpose of passing it on > to kmemleak(). So I don't know what that BUG_ON(slow_virt_to_phys() != > phys_addr) is supposed to tell us here. > It's only been nine years, so I'm sure Dave can remember why he added it ;) BUG_ON(slow_virt_to_phys((void *)x) != phys_addr); in arch/x86/mm/physaddr.c:__phys_addr(). This kfence patch does seem to be desirable, but we can't proceed if it's resulting in kernel crashes.
