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    SubjectRe: [syzbot? printk?] no WARN_ON() messages printed before "Kernel panic - not syncing: panic_on_warn set ..."
    On (03/19/19 09:10), Dmitry Vyukov wrote:

    [..]

    > In some setups we read out output with "dmesg -w" (should stream
    > output as well) in absence of a better solution. Will this be affected
    > by SYSLOG_ACTION_CLEAR?

    There is a small chance that syslog/devkmsg can be affected

    syslog_clear()
    {
    clear_seq = log_next_seq;
    clear_idx = log_next_idx;
    }

    syslog_print_all()
    {
    ...
    seq = clear_seq;
    idx = clear_idx;
    while (seq < log_next_seq) {
    ...
    len += msg_print_text(msg, true, time, NULL, 0);
    }
    ...
    }

    devkmsg also may be affected

    syslog_clear()
    {
    clear_seq = log_next_seq;
    clear_idx = log_next_idx;
    }

    devkmsg_llseek()
    {
    ...
    case SEEK_DATA:
    user->idx = clear_idx;
    user->seq = clear_seq;
    break;
    ...
    }

    user->idx/user->seq then are used in devkmsg poll()/read(). syslog is
    more likely to be affected, I think.

    -ss

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