57 lines
1.9 KiB
C
57 lines
1.9 KiB
C
/* SPDX-License-Identifier: GPL-2.0-or-later */
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/*
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* Copyright (c) 2020 SUSE LLC <mdoucha@suse.cz>
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*/
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#ifndef TST_MEMUTILS_H__
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#define TST_MEMUTILS_H__
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/*
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* Fill up to maxsize physical memory with fillchar, then free it for reuse.
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* If maxsize is zero, fill as much memory as possible. This function is
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* intended for data disclosure vulnerability tests to reduce the probability
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* that a vulnerable kernel will leak a block of memory that was full of
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* zeroes by chance.
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*
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* The function keeps a safety margin to avoid invoking OOM killer and
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* respects the limitations of available address space. (Less than 3GB can be
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* polluted on a 32bit system regardless of available physical RAM.)
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*/
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void tst_pollute_memory(size_t maxsize, int fillchar);
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/*
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* Read the value of MemAvailable from /proc/meminfo, if no support on
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* older kernels, return 'MemFree + Cached' for instead.
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*/
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long long tst_available_mem(void);
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/*
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* Enable OOM protection to prevent process($PID) being killed by OOM Killer.
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* echo -1000 >/proc/$PID/oom_score_adj
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*
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* If the pid is 0 which means it will set on current(self) process.
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*
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* Unless the process has CAP_SYS_RESOURCE this call will be no-op because
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* setting adj value < 0 requires it.
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*
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* CAP_SYS_RESOURCE:
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* set /proc/[pid]/oom_score_adj to a value lower than the value last set
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* by a process with CAP_SYS_RESOURCE.
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*
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* Note:
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* This exported tst_enable_oom_protection function can be used at anywhere
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* you want to protect, but please remember that if you do enable protection
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* on a process($PID) that all the children will inherit its score and be
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* ignored by OOM Killer as well. So that's why tst_disable_oom_protection()
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* to be used in combination.
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*/
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void tst_enable_oom_protection(pid_t pid);
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/*
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* Disable the OOM protection for the process($PID).
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* echo 0 >/proc/$PID/oom_score_adj
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*/
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void tst_disable_oom_protection(pid_t pid);
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#endif /* TST_MEMUTILS_H__ */
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