From 6c89368a9000426f4645cd6b32b082868cf72517 Mon Sep 17 00:00:00 2001
From: Luke Granger-Brown <hg@lukegb.com>
Date: Fri, 6 Nov 2020 05:03:19 +0000
Subject: [PATCH] 3p/nixpkgs: revert zram module

---
 .../nixpkgs/nixos/modules/config/zram.nix        | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/third_party/nixpkgs/nixos/modules/config/zram.nix b/third_party/nixpkgs/nixos/modules/config/zram.nix
index 5e9870bf6b..ef6e89599e 100644
--- a/third_party/nixpkgs/nixos/modules/config/zram.nix
+++ b/third_party/nixpkgs/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);
+                    ${if cfg.memoryMax != null then ''
+                      memory_max=int(${toString cfg.memoryMax}/${toString devicesCount});
+                      if (value > memory_max) { value = memory_max }
+                    '' else ""}
+                  print value
               }' /proc/meminfo)
 
               ${pkgs.utillinux}/sbin/zramctl --size $mem --algorithm ${cfg.algorithm} /dev/${dev}