5.4-stable review patch. If anyone has any objections, please let me know.
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From: Joel Savitz jsavitz@redhat.com
commit 8d98e42fb20c25e8efdab4cc1ac46d52ba964aca upstream.
commit 5ef64cc8987a ("mm: allow a controlled amount of unfairness in the page lock") introduced a new systctl but no accompanying documentation.
Add a simple entry to the documentation.
Link: https://lkml.kernel.org/r/20220325164437.120246-1-jsavitz@redhat.com Signed-off-by: Joel Savitz jsavitz@redhat.com Cc: Jonathan Corbet corbet@lwn.net Cc: Vlastimil Babka vbabka@suse.cz Cc: Mel Gorman mgorman@techsingularity.net Cc: Dave Hansen dave.hansen@linux.intel.com Cc: Suren Baghdasaryan surenb@google.com Cc: Mike Rapoport rppt@kernel.org Cc: "zhangyi (F)" yi.zhang@huawei.com Cc: Charan Teja Reddy charante@codeaurora.org Cc: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- Documentation/admin-guide/sysctl/vm.rst | 9 +++++++++ 1 file changed, 9 insertions(+)
--- a/Documentation/admin-guide/sysctl/vm.rst +++ b/Documentation/admin-guide/sysctl/vm.rst @@ -61,6 +61,7 @@ Currently, these files are in /proc/sys/ - overcommit_memory - overcommit_ratio - page-cluster +- page_lock_unfairness - panic_on_oom - percpu_pagelist_fraction - stat_interval @@ -741,6 +742,14 @@ extra faults and I/O delays for followin that consecutive pages readahead would have brought in.
+page_lock_unfairness +==================== + +This value determines the number of times that the page lock can be +stolen from under a waiter. After the lock is stolen the number of times +specified in this file (default is 5), the "fair lock handoff" semantics +will apply, and the waiter will only be awakened if the lock can be taken. + panic_on_oom ============