3p/nixpkgs: fix PR102855

third_party/nixpkgs/patches/pr102855-zram-allow-memorymax.patch

@@ -0,0 +1,57 @@
+From 961b7c7a6d47b224b2c3fea44ed18b722611d7ab Mon Sep 17 00:00:00 2001
+From: Luke Granger-Brown <git@lukegb.com>
+Date: Thu, 5 Nov 2020 02:29:46 +0000
+Subject: [PATCH] nixos/zram: add zramSwap.memoryMax option
+
+This allows capping the total amount of memory that will be used for
+zram-swap, in addition to the percentage-based calculation, which is
+useful when blanket-applying a configuration to many machines.
+
+This is based off the strategy used by Fedora for their rollout of
+zram-swap-by-default in Fedora 33
+(https://fedoraproject.org/wiki/Changes/SwapOnZRAM), which caps the
+maximum amount of memory used for zram at 4GiB.
+
+In future it might be good to port this to the systemd zram-generator,
+instead of using this separate infrastructure.
+---
+ nixos/modules/config/zram.nix | 16 +++++++++++++++-
+ 1 file changed, 15 insertions(+), 1 deletion(-)
+
+diff --git a/nixos/modules/config/zram.nix b/nixos/modules/config/zram.nix
+index 341101bc184..1f513b7e4da 100644
+--- a/nixos/modules/config/zram.nix
++++ b/nixos/modules/config/zram.nix
+@@ -80,6 +80,15 @@ in
+         '';
+       };
+ 
++      memoryMax = mkOption {
++        default = null;
++        type = with types; nullOr int;
++        description = ''
++          Maximum total amount of memory (in bytes) that can be used by the zram
++          swap devices.
++        '';
++      };
++
+       priority = mkOption {
+         default = 5;
+         type = types.int;
+@@ -146,7 +155,12 @@ in
+ 
+               # Calculate memory to use for zram
+               mem=$(${pkgs.gawk}/bin/awk '/MemTotal: / {
+-                  print int($2*${toString cfg.memoryPercent}/100.0/${toString devicesCount}*1024)
++                  value=int($2*${toString cfg.memoryPercent}/100.0/${toString devicesCount}*1024);
++                    ${lib.optionalString (cfg.memoryMax != null) ''
++                      memory_max=int(${toString cfg.memoryMax}/${toString devicesCount});
++                      if (value > memory_max) { value = memory_max }
++                    ''}
++                  print value
+               }' /proc/meminfo)
+ 
+               ${pkgs.util-linux}/sbin/zramctl --size $mem --algorithm ${cfg.algorithm} /dev/${dev}
+-- 
+2.29.2
+

third_party/nixpkgs/patches/series

@@ -1,3 +1,4 @@
+pr102855-zram-allow-memorymax.patch
 pr103084-teamspeak3-bump-3.5.6.patch
 pr104891-factorio-bump-1.1.1.patch
 pr105231-factorio-bump-1.1.2.patch