On 4 Dec 2024, at 5:41, Geert Uytterhoeven wrote: > Hi Zi, > > On Fri, Oct 11, 2024 at 5:13 PM Zi Yan <ziy@xxxxxxxxxx> wrote: >> Commit 6471384af2a6 ("mm: security: introduce init_on_alloc=1 and >> init_on_free=1 boot options") forces allocated page to be zeroed in >> post_alloc_hook() when init_on_alloc=1. >> >> For order-0 folios, if arch does not define >> vma_alloc_zeroed_movable_folio(), the default implementation again zeros >> the page return from the buddy allocator. So the page is zeroed twice. >> Fix it by passing __GFP_ZERO instead to avoid double page zeroing. >> At the moment, s390,arm64,x86,alpha,m68k are not impacted since they >> define their own vma_alloc_zeroed_movable_folio(). >> >> For >0 order folios (mTHP and PMD THP), folio_zero_user() is called to >> zero the folio again. Fix it by calling folio_zero_user() only if >> init_on_alloc is set. All arch are impacted. >> >> Added alloc_zeroed() helper to encapsulate the init_on_alloc check. >> >> Signed-off-by: Zi Yan <ziy@xxxxxxxxxx> > > Thanks for your patch, which is now commit 5708d96da20b99b4 ("mm: > avoid zeroing user movable page twice with init_on_alloc=1") > in v6.13-rc1. Thank you for reporting the error. > > This causing a panic when starting userspace on MIPS64 RBTX4927: > > Run /sbin/init as init process > process '/lib/systemd/systemd' started with executable stack > Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b > ---[ end Kernel panic - not syncing: Attempted to kill init! > exitcode=0x0000000b ]--- > > or > > Run /sbin/init as init process > process '/lib/systemd/systemd' started with executable stack > do_page_fault(): sending SIGSEGV to init for invalid read access > from 00000000583399f8 > epc = 0000000077e2b094 in ld-2.19.so[3094,77e28000+22000] > ra = 0000000077e2afcc in ld-2.19.so[2fcc,77e28000+22000] > Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b > ---[ end Kernel panic - not syncing: Attempted to kill init! > exitcode=0x0000000b ]--- > > or > > Run /sbin/init as init process > process '/lib/systemd/systemd' started with executable stack > /sbin/inKernel panic - not syncing: Attempted to kill init! > exitcode=0x00007f00 > ---[ end Kernel panic - not syncing: Attempted to kill init! > exitcode=0x00007f00 ]--- > it: error while loading shared libraries: libpthread.so.0: object > file has no dynamic section Do you mind providing the full kernel log for this panic? And your kernel config as well. I am trying to figure out why changing page zeroing from twice to once can cause kernel panic. -- Best Regards, Yan, Zi