Revision c403f6a3a792a6601185497c12b0bdf4be880439 authored by Qian Cai on 15 August 2020, 00:31:53 UTC, committed by Linus Torvalds on 15 August 2020, 02:56:57 UTC
BUG: KCSAN: data-race in page_cpupid_xchg_last / put_page write (marked) to 0xfffffc0d48ec1a00 of 8 bytes by task 91442 on cpu 3: page_cpupid_xchg_last+0x51/0x80 page_cpupid_xchg_last at mm/mmzone.c:109 (discriminator 11) wp_page_reuse+0x3e/0xc0 wp_page_reuse at mm/memory.c:2453 do_wp_page+0x472/0x7b0 do_wp_page at mm/memory.c:2798 __handle_mm_fault+0xcb0/0xd00 handle_pte_fault at mm/memory.c:4049 (inlined by) __handle_mm_fault at mm/memory.c:4163 handle_mm_fault+0xfc/0x2f0 handle_mm_fault at mm/memory.c:4200 do_page_fault+0x263/0x6f9 do_user_addr_fault at arch/x86/mm/fault.c:1465 (inlined by) do_page_fault at arch/x86/mm/fault.c:1539 page_fault+0x34/0x40 read to 0xfffffc0d48ec1a00 of 8 bytes by task 94817 on cpu 69: put_page+0x15a/0x1f0 page_zonenum at include/linux/mm.h:923 (inlined by) is_zone_device_page at include/linux/mm.h:929 (inlined by) page_is_devmap_managed at include/linux/mm.h:948 (inlined by) put_page at include/linux/mm.h:1023 wp_page_copy+0x571/0x930 wp_page_copy at mm/memory.c:2615 do_wp_page+0x107/0x7b0 __handle_mm_fault+0xcb0/0xd00 handle_mm_fault+0xfc/0x2f0 do_page_fault+0x263/0x6f9 page_fault+0x34/0x40 Reported by Kernel Concurrency Sanitizer on: CPU: 69 PID: 94817 Comm: systemd-udevd Tainted: G W O L 5.5.0-next-20200204+ #6 Hardware name: HPE ProLiant DL385 Gen10/ProLiant DL385 Gen10, BIOS A40 07/10/2019 A page never changes its zone number. The zone number happens to be stored in the same word as other bits which are modified, but the zone number bits will never be modified by any other write, so it can accept a reload of the zone bits after an intervening write and it don't need to use READ_ONCE(). Thus, annotate this data race using ASSERT_EXCLUSIVE_BITS() to also assert that there are no concurrent writes to it. Suggested-by: Marco Elver <elver@google.com> Signed-off-by: Qian Cai <cai@lca.pw> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: David Hildenbrand <david@redhat.com> Cc: Jan Kara <jack@suse.cz> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Ira Weiny <ira.weiny@intel.com> Cc: Dan Williams <dan.j.williams@intel.com> Link: http://lkml.kernel.org/r/1581619089-14472-1-git-send-email-cai@lca.pw Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent 7e0cc01
stackdelta
#!/usr/bin/env perl
# SPDX-License-Identifier: GPL-2.0
# Read two files produced by the stackusage script, and show the
# delta between them.
#
# Currently, only shows changes for functions listed in both files. We
# could add an option to show also functions which have vanished or
# appeared (which would often be due to gcc making other inlining
# decisions).
#
# Another possible option would be a minimum absolute value for the
# delta.
#
# A third possibility is for sorting by delta, but that can be
# achieved by piping to sort -k5,5g.
sub read_stack_usage_file {
my %su;
my $f = shift;
open(my $fh, '<', $f)
or die "cannot open $f: $!";
while (<$fh>) {
chomp;
my ($file, $func, $size, $type) = split;
# Old versions of gcc (at least 4.7) have an annoying quirk in
# that a (static) function whose name has been changed into
# for example ext4_find_unwritten_pgoff.isra.11 will show up
# in the .su file with a name of just "11". Since such a
# numeric suffix is likely to change across different
# commits/compilers/.configs or whatever else we're trying to
# tweak, we can't really track those functions, so we just
# silently skip them.
#
# Newer gcc (at least 5.0) report the full name, so again,
# since the suffix is likely to change, we strip it.
next if $func =~ m/^[0-9]+$/;
$func =~ s/\..*$//;
# Line numbers are likely to change; strip those.
$file =~ s/:[0-9]+$//;
$su{"${file}\t${func}"} = {size => $size, type => $type};
}
close($fh);
return \%su;
}
@ARGV == 2
or die "usage: $0 <old> <new>";
my $old = read_stack_usage_file($ARGV[0]);
my $new = read_stack_usage_file($ARGV[1]);
my @common = sort grep {exists $new->{$_}} keys %$old;
for (@common) {
my $x = $old->{$_}{size};
my $y = $new->{$_}{size};
my $delta = $y - $x;
if ($delta) {
printf "%s\t%d\t%d\t%+d\n", $_, $x, $y, $delta;
}
}
Computing file changes ...
