diff options
Diffstat (limited to 'target/linux/bcm27xx/patches-5.15/950-0800-mm-page_alloc-cma-introduce-a-customisable-threshold.patch')
| -rw-r--r-- | target/linux/bcm27xx/patches-5.15/950-0800-mm-page_alloc-cma-introduce-a-customisable-threshold.patch | 67 |
1 files changed, 67 insertions, 0 deletions
diff --git a/target/linux/bcm27xx/patches-5.15/950-0800-mm-page_alloc-cma-introduce-a-customisable-threshold.patch b/target/linux/bcm27xx/patches-5.15/950-0800-mm-page_alloc-cma-introduce-a-customisable-threshold.patch new file mode 100644 index 0000000000..91ec85a0b2 --- /dev/null +++ b/target/linux/bcm27xx/patches-5.15/950-0800-mm-page_alloc-cma-introduce-a-customisable-threshold.patch @@ -0,0 +1,67 @@ +From 6896ae528e4654e6f4bdff575337237f40de48b2 Mon Sep 17 00:00:00 2001 +From: David Plowman <david.plowman@raspberrypi.com> +Date: Tue, 29 Mar 2022 16:10:06 +0100 +Subject: [PATCH] mm,page_alloc,cma: introduce a customisable threshold + for allocating pages in cma + +On some platforms the cma area can be half the entire system memory, +meaning that allocations start happening in the cma area immediately. +This leads to fragmentation and subsequent fatal cma_alloc failures. + +We introduce an "alloc_in_cma_threshold" parameter which requires that +this many sixteenths of the free pages must be in cma before it will +try to use them. By default this is set to 12, but the previous +behaviour can be restored by setting it to 8 on startup. + +Signed-off-by: David Plowman <david.plowman@raspberrypi.com> +--- + mm/page_alloc.c | 28 +++++++++++++++++++++++++--- + 1 file changed, 25 insertions(+), 3 deletions(-) + +--- a/mm/page_alloc.c ++++ b/mm/page_alloc.c +@@ -190,6 +190,27 @@ EXPORT_SYMBOL(init_on_alloc); + DEFINE_STATIC_KEY_MAYBE(CONFIG_INIT_ON_FREE_DEFAULT_ON, init_on_free); + EXPORT_SYMBOL(init_on_free); + ++#define ALLOC_IN_CMA_THRESHOLD_MAX 16 ++#define ALLOC_IN_CMA_THRESHOLD_DEFAULT 12 ++ ++static unsigned long _alloc_in_cma_threshold __read_mostly ++ = ALLOC_IN_CMA_THRESHOLD_DEFAULT; ++ ++static int __init alloc_in_cma_threshold_setup(char *buf) ++{ ++ unsigned long res; ++ ++ if (kstrtoul(buf, 10, &res) < 0 || ++ res > ALLOC_IN_CMA_THRESHOLD_MAX) { ++ pr_err("Bad alloc_cma_threshold value\n"); ++ return 0; ++ } ++ _alloc_in_cma_threshold = res; ++ pr_info("Setting alloc_in_cma_threshold to %lu\n", res); ++ return 0; ++} ++early_param("alloc_in_cma_threshold", alloc_in_cma_threshold_setup); ++ + static bool _init_on_alloc_enabled_early __read_mostly + = IS_ENABLED(CONFIG_INIT_ON_ALLOC_DEFAULT_ON); + static int __init early_init_on_alloc(char *buf) +@@ -2980,12 +3001,13 @@ __rmqueue(struct zone *zone, unsigned in + if (IS_ENABLED(CONFIG_CMA)) { + /* + * Balance movable allocations between regular and CMA areas by +- * allocating from CMA when over half of the zone's free memory +- * is in the CMA area. ++ * allocating from CMA when over more than a given proportion of ++ * the zone's free memory is in the CMA area. + */ + if (alloc_flags & ALLOC_CMA && + zone_page_state(zone, NR_FREE_CMA_PAGES) > +- zone_page_state(zone, NR_FREE_PAGES) / 2) { ++ zone_page_state(zone, NR_FREE_PAGES) / ALLOC_IN_CMA_THRESHOLD_MAX ++ * _alloc_in_cma_threshold) { + page = __rmqueue_cma_fallback(zone, order); + if (page) + goto out; |