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    SubjectRe: [PATCH 2/2] fs, elf: drop MAP_FIXED usage from elf_map
    On Wed 18-04-18 20:43:11, Tetsuo Handa wrote:
    > Michal Hocko wrote:
    > > > Don't complain if IS_ERR_VALUE(),
    > >
    > > this is simply wrong. We do want to warn on the failure because this is
    > > when the actual clash happens. We should just warn on EEXIST.
    >
    > >From 25442cdd31aa5cc8522923a0153a77dfd2ebc832 Mon Sep 17 00:00:00 2001
    > From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
    > Date: Wed, 18 Apr 2018 20:38:15 +0900
    > Subject: [PATCH] fs, elf: don't complain MAP_FIXED_NOREPLACE unless -EEXIST
    > error.
    >
    > Commit 4ed28639519c7bad ("fs, elf: drop MAP_FIXED usage from elf_map") is
    > printing spurious messages under memory pressure due to map_addr == -ENOMEM.
    >
    > 9794 (a.out): Uhuuh, elf segment at 00007f2e34738000(fffffffffffffff4) requested but the memory is mapped already
    > 14104 (a.out): Uhuuh, elf segment at 00007f34fd76c000(fffffffffffffff4) requested but the memory is mapped already
    > 16843 (a.out): Uhuuh, elf segment at 00007f930ecc7000(fffffffffffffff4) requested but the memory is mapped already
    >
    > Complain only if -EEXIST, and use %px for printing the address.

    Yes this is better. But...

    [...]
    > - if ((type & MAP_FIXED_NOREPLACE) && BAD_ADDR(map_addr))
    > - pr_info("%d (%s): Uhuuh, elf segment at %p requested but the memory is mapped already\n",
    > - task_pid_nr(current), current->comm,
    > - (void *)addr);
    > + if ((type & MAP_FIXED_NOREPLACE) && map_addr == -EEXIST)

    ... please use PTR_ERR(map_addr) == -EEXIST

    then you can add
    Acked-by: Michal Hocko <mhocko@suse.com>

    > + pr_info("%d (%s): Uhuuh, elf segment at %px requested but the memory is mapped already\n",
    > + task_pid_nr(current), current->comm, (void *)addr);
    >
    > return(map_addr);
    > }
    > --
    > 1.8.3.1

    --
    Michal Hocko
    SUSE Labs

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