• Steven Price's avatar
    x86: mm: avoid allocating struct mm_struct on the stack · e47690d7
    Steven Price authored
    struct mm_struct is quite large (~1664 bytes) and so allocating on the
    stack may cause problems as the kernel stack size is small.
    
    Since ptdump_walk_pgd_level_core() was only allocating the structure so
    that it could modify the pgd argument we can instead introduce a pgd
    override in struct mm_walk and pass this down the call stack to where it
    is needed.
    
    Since the correct mm_struct is now being passed down, it is now also
    unnecessary to take the mmap_sem semaphore because ptdump_walk_pgd() will
    now take the semaphore on the real mm.
    
    [steven.price@arm.com: restore missed arm64 changes]
      Link: http://lkml.kernel.org/r/20200108145710.34314-1-steven.price@arm.com
    Link: http://lkml.kernel.org/r/20200108145710.34314-1-steven.price@arm.comSigned-off-by: default avatarSteven Price <steven.price@arm.com>
    Reported-by: default avatarStephen Rothwell <sfr@canb.auug.org.au>
    Cc: Catalin Marinas <catalin.marinas@arm.com>
    Cc: Albert Ou <aou@eecs.berkeley.edu>
    Cc: Alexandre Ghiti <alex@ghiti.fr>
    Cc: Andy Lutomirski <luto@kernel.org>
    Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
    Cc: Arnd Bergmann <arnd@arndb.de>
    Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
    Cc: Borislav Petkov <bp@alien8.de>
    Cc: Christian Borntraeger <borntraeger@de.ibm.com>
    Cc: Dave Hansen <dave.hansen@linux.intel.com>
    Cc: David S. Miller <davem@davemloft.net>
    Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
    Cc: "H. Peter Anvin" <hpa@zytor.com>
    Cc: Ingo Molnar <mingo@redhat.com>
    Cc: James Hogan <jhogan@kernel.org>
    Cc: James Morse <james.morse@arm.com>
    Cc: Jerome Glisse <jglisse@redhat.com>
    Cc: "Liang, Kan" <kan.liang@linux.intel.com>
    Cc: Mark Rutland <mark.rutland@arm.com>
    Cc: Michael Ellerman <mpe@ellerman.id.au>
    Cc: Paul Burton <paul.burton@mips.com>
    Cc: Paul Mackerras <paulus@samba.org>
    Cc: Paul Walmsley <paul.walmsley@sifive.com>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Ralf Baechle <ralf@linux-mips.org>
    Cc: Russell King <linux@armlinux.org.uk>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: Vasily Gorbik <gor@linux.ibm.com>
    Cc: Vineet Gupta <vgupta@synopsys.com>
    Cc: Will Deacon <will@kernel.org>
    Cc: Zong Li <zong.li@sifive.com>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    e47690d7
pagewalk.c 14.2 KB