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Revision 7ff57e98fb78ad94edafbdc7435f2d745e9e6bb5 authored by Fabio M. De Francesco on 23 February 2022, 10:02:52 UTC, committed by Jakub Kicinski on 24 February 2022, 17:09:33 UTC 
net/smc: Use a mutex for locking "struct smc_pnettable"
 
smc_pnetid_by_table_ib() uses read_lock() and then it calls smc_pnet_apply_ib()
which, in turn, calls mutex_lock(&smc_ib_devices.mutex).

read_lock() disables preemption. Therefore, the code acquires a mutex while in
atomic context and it leads to a SAC bug.

Fix this bug by replacing the rwlock with a mutex.

Reported-and-tested-by: syzbot+4f322a6d84e991c38775@syzkaller.appspotmail.com
Fixes: 64e28b52c7a6 ("net/smc: add pnet table namespace support")
Confirmed-by: Tony Lu <tonylu@linux.alibaba.com>
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Acked-by: Karsten Graul <kgraul@linux.ibm.com>
Link: https://lore.kernel.org/r/20220223100252.22562-1-fmdefrancesco@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Raw File
show_mem.c 
// SPDX-License-Identifier: GPL-2.0-only
/*
 * Generic show_mem() implementation
 *
 * Copyright (C) 2008 Johannes Weiner <hannes@saeurebad.de>
 */

#include <linux/mm.h>
#include <linux/cma.h>

void show_mem(unsigned int filter, nodemask_t *nodemask)
{
	pg_data_t *pgdat;
	unsigned long total = 0, reserved = 0, highmem = 0;

	printk("Mem-Info:\n");
	show_free_areas(filter, nodemask);

	for_each_online_pgdat(pgdat) {
		int zoneid;

		for (zoneid = 0; zoneid < MAX_NR_ZONES; zoneid++) {
			struct zone *zone = &pgdat->node_zones[zoneid];
			if (!populated_zone(zone))
				continue;

			total += zone->present_pages;
			reserved += zone->present_pages - zone_managed_pages(zone);

			if (is_highmem_idx(zoneid))
				highmem += zone->present_pages;
		}
	}

	printk("%lu pages RAM\n", total);
	printk("%lu pages HighMem/MovableOnly\n", highmem);
	printk("%lu pages reserved\n", reserved);
#ifdef CONFIG_CMA
	printk("%lu pages cma reserved\n", totalcma_pages);
#endif
#ifdef CONFIG_MEMORY_FAILURE
	printk("%lu pages hwpoisoned\n", atomic_long_read(&num_poisoned_pages));
#endif
}
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