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authorMikulas Patocka <mpatocka@redhat.com>2017-04-30 23:34:53 +0200
committerMike Snitzer <snitzer@redhat.com>2017-05-01 21:21:42 +0200
commit390020ad2af9ca04844c4f3b1f299ad8746d84c8 (patch)
treea89be3c8cd0ad3b0959c12eb534c288be9669597 /drivers/md/Makefile
parentdm bufio: avoid a possible ABBA deadlock (diff)
downloadlinux-390020ad2af9ca04844c4f3b1f299ad8746d84c8.tar.xz
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dm bufio: check new buffer allocation watermark every 30 seconds
dm-bufio checks a watermark when it allocates a new buffer in __bufio_new(). However, it doesn't check the watermark when the user changes /sys/module/dm_bufio/parameters/max_cache_size_bytes. This may result in a problem - if the watermark is high enough so that all possible buffers are allocated and if the user lowers the value of "max_cache_size_bytes", the watermark will never be checked against the new value because no new buffer would be allocated. To fix this, change __evict_old_buffers() so that it checks the watermark. __evict_old_buffers() is called every 30 seconds, so if the user reduces "max_cache_size_bytes", dm-bufio will react to this change within 30 seconds and decrease memory consumption. Depends-on: 1b0fb5a5b2 ("dm bufio: avoid a possible ABBA deadlock") Cc: stable@vger.kernel.org Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
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