Hi Akashi, On 15/03/17 09:59, AKASHI Takahiro wrote: > Since arch_kexec_protect_crashkres() removes a mapping for crash dump > kernel image, the loaded data won't be preserved around hibernation. > > In this patch, helper functions, kexec_prepare_suspend()/ > kexec_post_resume(), are additionally called before/after hibernation so > that the relevant memory segments will be mapped again and preserved just > as the others are. > > In addition, to minimize the size of hibernation image, > kexec_is_chraskres_nosave() is added to pfn_is_nosave() in order to
(crashkres) > recoginize only the pages that hold loaded crash dump kernel image as (recognize) > saveable. Hibernation excludes any pages that are marked as Reserved and > yet "nosave." Neat! I didn't think this would be possible without hacking kernel/power/snapshot.c. I've given this a spin on Juno and Seattle, I even added debug_pagealloc, but that doesn't trick it because your kexec_prepare_suspend() puts the mapping back. Reviewed-by: James Morse <[email protected]> Thanks, James Some nits about comments: > diff --git a/arch/arm64/kernel/hibernate.c b/arch/arm64/kernel/hibernate.c > index 97a7384100f3..1e10fafa59bd 100644 > --- a/arch/arm64/kernel/hibernate.c > +++ b/arch/arm64/kernel/hibernate.c > @@ -286,6 +288,9 @@ int swsusp_arch_suspend(void) > local_dbg_save(flags); > > if (__cpu_suspend_enter(&state)) { > + /* make the crash dump kernel image visible/saveable */ > + kexec_prepare_suspend(); Strictly this is kdump not kexec, but the comment makes that clear. > + > sleep_cpu = smp_processor_id(); > ret = swsusp_save(); > } else { > diff --git a/arch/arm64/kernel/machine_kexec.c > b/arch/arm64/kernel/machine_kexec.c > index 02e4f929db3b..82f48db589cf 100644 > --- a/arch/arm64/kernel/machine_kexec.c > +++ b/arch/arm64/kernel/machine_kexec.c > @@ -220,7 +221,6 @@ void arch_kexec_protect_crashkres(void) > kexec_crash_image->segment[i].memsz, > PAGE_KERNEL_INVALID, true); > > - Stray whitespace change from a previous patch? > flush_tlb_all(); > } > > @@ -233,3 +233,74 @@ void arch_kexec_unprotect_crashkres(void) > +/* > + * kexec_is_crashres_nosave > + * > + * Return true only if a page is part of reserved memory for crash dump > kernel, > + * but does not hold any data of loaded kernel image. > + * > + * Note that all the pages in crash dump kernel memory have been initially > + * marked as Reserved in kexec_reserve_crashkres_pages(). > + * > + * In hibernation, the pages which are Reserved and yet "nosave" > + * are excluded from the hibernation iamge. kexec_is_crashkres_nosave() > + * does this check for crash dump kernel and will reduce the total size > + * of hibernation image. > + */ > + > +bool kexec_is_crashkres_nosave(unsigned long pfn) > +{ > + int i; > + phys_addr_t addr; > + > + /* in reserved memory? */ Comment in the wrong place? > + if (!crashk_res.end) > + return false; > + > + addr = __pfn_to_phys(pfn); (makes more sense here) > + if ((addr < crashk_res.start) || (crashk_res.end < addr)) > + return false; > + > + /* not part of loaded kernel image? */ Comment in the wrong place? > + if (!kexec_crash_image) > + return true; > + (makes more sense here) > + for (i = 0; i < kexec_crash_image->nr_segments; i++) > + if (addr >= kexec_crash_image->segment[i].mem && > + addr < (kexec_crash_image->segment[i].mem + > + kexec_crash_image->segment[i].memsz)) > + return false; > + > + return true; > +} > + Thanks, James _______________________________________________ kexec mailing list [email protected] http://lists.infradead.org/mailman/listinfo/kexec
