• Jeremy Fitzhardinge's avatar
    [PATCH] x86: deflate stack usage in lib/inflate.c · 35c74226
    Jeremy Fitzhardinge authored
    inflate_fixed and huft_build together use around 2.7k of stack.  When
    using 4k stacks, I saw stack overflows from interrupts arriving while
    unpacking the root initrd:
    do_IRQ: stack overflow: 384
     [<c0106b64>] show_trace_log_lvl+0x1a/0x30
     [<c01075e6>] show_trace+0x12/0x14
     [<c010763f>] dump_stack+0x16/0x18
     [<c0107ca4>] do_IRQ+0x6d/0xd9
     [<c010202b>] xen_evtchn_do_upcall+0x6e/0xa2
     [<c0106781>] xen_hypervisor_callback+0x25/0x2c
     [<c010116c>] xen_restore_fl+0x27/0x29
     [<c0330f63>] _spin_unlock_irqrestore+0x4a/0x50
     [<c0117aab>] change_page_attr+0x577/0x584
     [<c0117b45>] kernel_map_pages+0x8d/0xb4
     [<c016a314>] cache_alloc_refill+0x53f/0x632
     [<c016a6c2>] __kmalloc+0xc1/0x10d
     [<c0463d34>] malloc+0x10/0x12
     [<c04641c1>] huft_build+0x2a7/0x5fa
     [<c04645a5>] inflate_fixed+0x91/0x136
     [<c04657e2>] unpack_to_rootfs+0x5f2/0x8c1
     [<c0465acf>] populate_rootfs+0x1e/0xe4
    (This was under Xen, but there's no reason it couldn't happen on bare
    This patch mallocs the local variables, thereby reducing the stack
    usage to sane levels.
    Also, up the heap size for the kernel decompressor to deal with the
    extra allocation.
    Signed-off-by: default avatarJeremy Fitzhardinge <jeremy@xensource.com>
    Signed-off-by: default avatarAndi Kleen <ak@suse.de>
    Cc: Tim Yamin <plasmaroo@gentoo.org>
    Cc: Andi Kleen <ak@suse.de>
    Cc: Matt Mackall <mpm@selenic.com>
    Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
    Cc: Richard Henderson <rth@twiddle.net>
    Cc: Russell King <rmk@arm.linux.org.uk>
    Cc: Ian Molton <spyro@f2s.com>
inflate.c 37.5 KB