> On Sep 28, 2020, at 11:02 AM, Nick Terrell <terrelln@xxxxxx> wrote: > > > >> On Sep 28, 2020, at 1:55 AM, Feng Tang <feng.tang@xxxxxxxxx> wrote: >> >> Hi Nick, >> >> 0day has found some kernel decomprssion failure case since 5.9-rc1 (X86_32 >> build), and it could be related with ZSTD code, though initially we bisected >> to some other commits. >> >> The error messages are: >> >> early console in setup code >> Wrong EFI loader signature. >> early console in extract_kernel >> input_data: 0x046f50b4 >> input_len: 0x01ebbeb6 >> output: 0x01000000 >> output_len: 0x04fc535c >> kernel_total_size: 0x055f5000 >> needed_size: 0x055f5000 >> >> Decompressing Linux... >> >> ZSTD-compressed data is corrupt >> >> This could be reproduced by compiling the kernel with attached config, >> and use QEMU to boot it. >> >> We suspect it could be related with the kernel size, as we only see >> it on big kernel, and some more info are: >> >> * If we remove a lot of kernel config to build a much smaller kernel, >> it will boot fine >> >> * If we change the zstd algorithm from zstd22 to zstd19, the kernel will >> boot fine with below patch >> >> diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile >> index 3962f59..8fe71ba 100644 >> --- a/arch/x86/boot/compressed/Makefile >> +++ b/arch/x86/boot/compressed/Makefile >> @@ -147,7 +147,7 @@ $(obj)/vmlinux.bin.lzo: $(vmlinux.bin.all-y) FORCE >> $(obj)/vmlinux.bin.zst: $(vmlinux.bin.all-y) FORCE >> - $(call if_changed,zstd22) >> + $(call if_changed,zstd) >> >> >> Please let me know if you need more info, and sorry for the late report >> as we just tracked down to this point. > > Thanks for the report, I will look into it today. CC: Petr Malat I’ve successfully reproduced, and found the issue. It turns out that this patch [0] from Petr Malat fixes the issue. As I mentioned in that thread, his fix corresponds to this upstream commit [1]. Can we get Petr's patch merged into v5.9? This bug only happens when the window size is > 8 MB. A non-kernel workaround would be to compress the kernel level 19 instead of level 22, which uses an 8 MB window size, instead of a 128 MB window size. The reason it only shows up for large kernels, is that the code is only buggy when an offset > 8 MB is used, so a kernel <= 8 MB can't trigger the bug. Best, Nick [0] https://lkml.org/lkml/2020/9/14/94 [1] https://github.com/facebook/zstd/commit/8a5c0c98ae5a7884694589d7a69bc99011add94d > Best, > Nick > >> Thanks, >> Feng >> >> >> >> <zstd_x86_32.config>
