summaryrefslogtreecommitdiffstats
path: root/debian/patches-rt/0030-highmem-Make-DEBUG_HIGHMEM-functional.patch
diff options
context:
space:
mode:
authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-27 10:06:00 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-27 10:06:00 +0000
commitb15a952c52a6825376d3e7f6c1bf5c886c6d8b74 (patch)
tree1500f2f8f276908a36d8126cb632c0d6b1276764 /debian/patches-rt/0030-highmem-Make-DEBUG_HIGHMEM-functional.patch
parentAdding upstream version 5.10.209. (diff)
downloadlinux-b15a952c52a6825376d3e7f6c1bf5c886c6d8b74.tar.xz
linux-b15a952c52a6825376d3e7f6c1bf5c886c6d8b74.zip
Adding debian version 5.10.209-2.debian/5.10.209-2debian
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'debian/patches-rt/0030-highmem-Make-DEBUG_HIGHMEM-functional.patch')
-rw-r--r--debian/patches-rt/0030-highmem-Make-DEBUG_HIGHMEM-functional.patch61
1 files changed, 61 insertions, 0 deletions
diff --git a/debian/patches-rt/0030-highmem-Make-DEBUG_HIGHMEM-functional.patch b/debian/patches-rt/0030-highmem-Make-DEBUG_HIGHMEM-functional.patch
new file mode 100644
index 000000000..139157832
--- /dev/null
+++ b/debian/patches-rt/0030-highmem-Make-DEBUG_HIGHMEM-functional.patch
@@ -0,0 +1,61 @@
+From 4c9348bc5b225c2de1552b059787335345d30d2c Mon Sep 17 00:00:00 2001
+From: Thomas Gleixner <tglx@linutronix.de>
+Date: Tue, 3 Nov 2020 10:27:19 +0100
+Subject: [PATCH 030/323] highmem: Make DEBUG_HIGHMEM functional
+Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/5.10/older/patches-5.10.204-rt100.tar.xz
+
+For some obscure reason when CONFIG_DEBUG_HIGHMEM is enabled the stack
+depth is increased from 20 to 41. But the only thing DEBUG_HIGHMEM does is
+to enable a few BUG_ON()'s in the mapping code.
+
+That's a leftover from the historical mapping code which had fixed entries
+for various purposes. DEBUG_HIGHMEM inserted guard mappings between the map
+types. But that got all ditched when kmap_atomic() switched to a stack
+based map management. Though the WITH_KM_FENCE magic survived without being
+functional. All the thing does today is to increase the stack depth.
+
+Add a working implementation to the generic kmap_local* implementation.
+
+Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
+Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
+---
+ mm/highmem.c | 14 ++++++++++++--
+ 1 file changed, 12 insertions(+), 2 deletions(-)
+
+diff --git a/mm/highmem.c b/mm/highmem.c
+index bb4ce13ee7e7..67d2d5983cb0 100644
+--- a/mm/highmem.c
++++ b/mm/highmem.c
+@@ -376,9 +376,19 @@ EXPORT_SYMBOL(kunmap_high);
+
+ static DEFINE_PER_CPU(int, __kmap_local_idx);
+
++/*
++ * With DEBUG_HIGHMEM the stack depth is doubled and every second
++ * slot is unused which acts as a guard page
++ */
++#ifdef CONFIG_DEBUG_HIGHMEM
++# define KM_INCR 2
++#else
++# define KM_INCR 1
++#endif
++
+ static inline int kmap_local_idx_push(void)
+ {
+- int idx = __this_cpu_inc_return(__kmap_local_idx) - 1;
++ int idx = __this_cpu_add_return(__kmap_local_idx, KM_INCR) - 1;
+
+ WARN_ON_ONCE(in_irq() && !irqs_disabled());
+ BUG_ON(idx >= KM_MAX_IDX);
+@@ -392,7 +402,7 @@ static inline int kmap_local_idx(void)
+
+ static inline void kmap_local_idx_pop(void)
+ {
+- int idx = __this_cpu_dec_return(__kmap_local_idx);
++ int idx = __this_cpu_sub_return(__kmap_local_idx, KM_INCR);
+
+ BUG_ON(idx < 0);
+ }
+--
+2.43.0
+