On Mon, Oct 31, 2022 at 10:05:58AM +0000, John Thomson wrote: > On Mon, 31 Oct 2022, at 02:36, Feng Tang wrote: > > Hi John, > > > > Thanks for the bisecting and reporting! > > > > On Mon, Oct 31, 2022 at 05:30:24AM +0800, Vlastimil Babka wrote: > >> On 10/30/22 20:23, John Thomson wrote: > >> > On Tue, 13 Sep 2022, at 06:54, Feng Tang wrote: > >> >> kmalloc's API family is critical for mm, with one nature that it will > >> >> round up the request size to a fixed one (mostly power of 2). Say > >> >> when user requests memory for '2^n + 1' bytes, actually 2^(n+1) bytes > >> >> could be allocated, so in worst case, there is around 50% memory > >> >> space waste. > >> > > >> > > >> > I have a ralink mt7621 router running Openwrt, using the mips ZBOOT kernel, and appear to have bisected > >> > a very-nearly-clean kernel v6.1rc-2 boot issue to this commit. > >> > I have 3 commits atop 6.1-rc2: fix a ZBOOT compile error, use the Openwrt LZMA options, > >> > and enable DEBUG_ZBOOT for my platform. I am compiling my kernel within the Openwrt build system. > >> > No guarantees this is not due to something I am doing wrong, but any insight would be greatly appreciated. > >> > > >> > > >> > On UART, No indication of the (once extracted) kernel booting: > >> > > >> > transfer started ......................................... transfer ok, time=2.01s > >> > setting up elf image... OK > >> > jumping to kernel code > >> > zimage at: 80BA4100 810D4720 > >> > Uncompressing Linux at load address 80001000 > >> > Copy device tree to address 80B96EE0 > >> > Now, booting the kernel... > >> > >> It's weird that the commit would cause no output so early, SLUB code is > >> run only later. > > > > I noticed your cmdline has console setting, could you enable the > > earlyprintk in cmdline like "earlyprintk=ttyS0,115200" etc to see > > if there is more message printed out. > > Still nothing from vmlinux with earlykprint on UART unless revert. > > > > > Also I want to confirm this is a boot failure and not only a boot > > message missing. > > Yes, boot failure. > Network comes up automatically on successful boot. Not happening when no kernel UART It is really weird that I see no boot issue on my MIPS emulation with almost same config, with different target - Malta board that QEMU supports. it just boot fine. Can you attach debugger to the board? (Which I hadn't tried. I had tried it only to QEMU) [...] > >> > > >> > > >> > possibly relevant config options: > >> > grep -E '(SLUB|SLAB)' .config > >> > # SLAB allocator options > >> > # CONFIG_SLAB is not set > >> > CONFIG_SLUB=y > >> > CONFIG_SLAB_MERGE_DEFAULT=y > >> > # CONFIG_SLAB_FREELIST_RANDOM is not set > >> > # CONFIG_SLAB_FREELIST_HARDENED is not set > >> > # CONFIG_SLUB_STATS is not set > >> > CONFIG_SLUB_CPU_PARTIAL=y > >> > # end of SLAB allocator options > >> > # CONFIG_SLUB_DEBUG is not set > >> > >> Also not having CONFIG_SLUB_DEBUG enabled means most of the code the > >> patch/commit touches is not even active. > >> Could this be some miscompile or code layout change exposing some > >> different bug, hmm. > > Yes, it could be. What happens with clang? > > >> Is it any different if you do enable CONFIG_SLUB_DEBUG ? > > No change > > >> Or change to CONFIG_SLAB? (that would be really weird if not) > > This boots fine > > > I haven't found any clue from the code either, and I compiled > > kernel with the config above and tested booting on an Alder-lake > > desktop and a QEMU, which boot fine. > > > > Could you provide the full kernel config and demsg (in compressed > > format if you think it's too big), so we can check more? > > Attached > > > Thanks, > > Feng > > vmlinux is bigger, and entry point is larger (0x8074081c vs 0x807407dc revert vs 0x8073fcbc), > so that may be it? Or not? > revert + SLUB_DEBUG + SLUB_DEBUG_ON is bigger still, but does successfully boot. > vmlinux entry point is 0x8074705c > > > transfer started ......................................... transfer ok, time=2.01s > setting up elf image... OK > jumping to kernel code > zimage at: 80BA4100 810D6FA0 > Uncompressing Linux at load address 80001000 > Copy device tree to address 80B9EEE0 > Now, booting the kernel... > [ 0.000000] Linux version 6.1.0-rc2 (john@john) (mipsel-openwrt-linux-musl-gc > c (OpenWrt GCC 11.3.0 r19724+16-1521d5f453) 11.3.0, GNU ld (GNU Binutils) 2.37) > #0 SMP Fri Oct 28 03:48:10 2022 > > > I will keep looking. > > Thank you, > -- > John Thomson -- Thanks, Hyeonggon
