On Tue, Oct 11, 2022 at 5:51 PM Liam Howlett <liam.howlett@xxxxxxxxxx> wrote: > > * Lukas Bulwahn <lukas.bulwahn@xxxxxxxxx> [221011 12:35]: > > Dear Liam, dear Matthew, dear all, > > > > The reproducer for the 'memory leak in __anon_vma_prepare' bug (see > > https://elisa-builder-00.iol.unh.edu/syzkaller-next/report?id=3113810b9abd3dfeb581759df93d3171d1a90f18) > > is reproducible, it is triggering the memory leak on the current > > mainline (commit 60bb8154d1d7), and it was not triggering on v6.0. My > > build config is a x86_64 defconfig. > > > > My git bisection showed that: > > > > 524e00b36e8c547f5582eef3fb645a8d9fc5e3df is the first bad commit > > commit 524e00b36e8c547f5582eef3fb645a8d9fc5e3df > > Author: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx> > > Date: Tue Sep 6 19:48:48 2022 +0000 > > > > The git bisect log is below, note that the commits 7fdbd37da5c6, > > d0cf3dd47f0d and 0c563f148043 are marked good in the git bisect as > > they caused bugs "BUG: Bad rss-counter state mm: ... type:MM_ANONPAGES > > val:2". This bug report might have overshadowed the actual issue, and > > hence the bug might have been introduced earlier, but was only visible > > once the Bad rss-counter state bug disappeared. > > > > > > ... > > > # first bad commit: [524e00b36e8c547f5582eef3fb645a8d9fc5e3df] mm: > > remove rb tree. > > > > > > If there is more information needed or other bisection to be done, > > please let me know. > > > Lukas, > > Thanks for the report. I am trying to reproduce this issue and have not > been able to trigger a memory leak. So far I have built using the > defconfig from arch/x86/configs/x86_64_defconfig and run the C code from > the end of your report above. It also produces some output that is not > captured in your report. Are you sure it's the defconfig being used? > > ------ > # ./repro > write to /proc/sys/kernel/hung_task_check_interval_secs failed: No such > file or directory > write to /proc/sys/net/core/bpf_jit_kallsyms failed: No such file or > directory > write to /proc/sys/net/core/bpf_jit_harden failed: No such file or > directory > write to /proc/sys/kernel/softlockup_all_cpu_backtrace failed: No such > file or directory > ------ > > Note your output does not mention softlockup or hung_task issues. This > is on 6.0.0-rc3-00207-g524e00b36e8c. It is also worth noting that the > resulting kernel does not have /sys/kernel/debug/kmemleak. > > I have also tested your reproducer with my own config which does have > the kmemleak debug file, but it did not trigger a memory leak either. I > suspect I am missing a config option? Are you using gcc or clang? > Liam, This is how I am building the kernel: make O=$BUILD defconfig && make O=$BUILD kvm_guest.config && \ ./scripts/kconfig/merge_config.sh -O $BUILD -r $BUILD/.config kernel/configs/syzkaller-recommended.config && \ make O=$BUILD -j`nproc` My syzkaller-recommended.config is: CONFIG_KCOV=y CONFIG_KCOV_INSTRUMENT_ALL=y CONFIG_KCOV_ENABLE_COMPARISONS=y CONFIG_DEBUG_FS=y CONFIG_DEBUG_KMEMLEAK=y CONFIG_DEBUG_INFO=y CONFIG_DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT=y CONFIG_KALLSYMS=y CONFIG_KALLSYMS_ALL=y CONFIG_CONFIGFS_FS=y CONFIG_SECURITYFS=y # CONFIG_RANDOMIZE_BASE is not set CONFIG_KASAN=y CONFIG_KASAN_INLINE=y CONFIG_FAULT_INJECTION=y CONFIG_FAULT_INJECTION_DEBUG_FS=y CONFIG_FAULT_INJECTION_USERCOPY=y CONFIG_FAILSLAB=y CONFIG_FAIL_PAGE_ALLOC=y CONFIG_FAIL_MAKE_REQUEST=y CONFIG_FAIL_IO_TIMEOUT=y CONFIG_FAIL_FUTEX=y CONFIG_LOCKDEP=y CONFIG_PROVE_LOCKING=y CONFIG_DEBUG_ATOMIC_SLEEP=y CONFIG_PROVE_RCU=y CONFIG_DEBUG_VM=y CONFIG_FORTIFY_SOURCE=y CONFIG_HARDENED_USERCOPY=y CONFIG_LOCKUP_DETECTOR=y CONFIG_SOFTLOCKUP_DETECTOR=y CONFIG_HARDLOCKUP_DETECTOR=y CONFIG_BOOTPARAM_HARDLOCKUP_PANIC=y CONFIG_DETECT_HUNG_TASK=y CONFIG_WQ_WATCHDOG=y CONFIG_DEFAULT_HUNG_TASK_TIMEOUT=140 CONFIG_RCU_CPU_STALL_TIMEOUT=100 So, it is "defconfig" + syzkaller debug features; sorry for being a bit too brief in my first report. The gcc version is: gcc (Debian 8.3.0-6) 8.3.0 Copyright (C) 2018 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. But I doubt that the gcc version is really relevant. I am running this in a pretty simple qemu instance. I can provide more information on my qemu setup if needed. Lukas
