In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
blk-iolatency: clear delay state when freeing policy data<\/p>\n
io.latency can throttle a group which has no latency target of its own.
\nWhen a sibling misses its target, check_scale_change() scales down its
\npeers, and a peer that reaches queue depth one gets blkcg_use_delay()
\ncalled on it on every further scale-down, even with min_lat_nsec == 0.<\/p>\n
iolatency_pd_offline() resets the target through
\niolatency_set_min_lat_nsec(), which clears the delay only on a nonzero
\nto zero transition, so it never clears such a peer. Freeing the policy
\ndata then leaves blkg->use_delay set and blkcg->congestion_count
\nelevated with nothing left that can drop it.<\/p>\n
blk_cgroup_congested() then returns true for every task in that cgroup
\nand its descendants for as long as the cgroup lives: page_cache_sync_ra()
\ncuts readahead to a single page, page_cache_async_ra() skips it
\naltogether, and __folio_throttle_swaprate() takes swap_avail_lock and
\nschedules a throttle on anonymous folio allocation.<\/p>\n
Clear the delay in iolatency_pd_free(). By then bio-held blkg
\nreferences have drained, or the queue is frozen for policy
\ndeactivation, so check_scale_change() cannot re-arm it. The free
\ncallback can also see policy data which was never attached to a blkg,
\nhence the pd->blkg check.<\/p>\n","protected":false},"excerpt":{"rendered":"
In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
blk-iolatency: clear delay state when freeing policy data<\/p>\n
io.latency can throttle a group which has no latency target of its own.<\/p>\n","protected":false},"template":"","meta":[],"categories":[],"tags":[],"class_list":["post-25592","vuln","type-vuln","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln\/25592","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln"}],"about":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/types\/vuln"}],"wp:attachment":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=25592"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=25592"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=25592"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}