diff options
| author | Johannes Berg <johannes.berg@intel.com> | 2021-01-10 19:05:08 +0100 |
|---|---|---|
| committer | Richard Weinberger <richard@nod.at> | 2021-01-26 22:11:38 +0100 |
| commit | 2fcb4090cd7352665ecb756990a3087bfd86a295 (patch) | |
| tree | 4562c5264a7b6326b8cdf82ebe379bc351ab58d4 /arch/um/kernel | |
| parent | f4172b084342fd3f9e38c10650ffe19eac30d8ce (diff) | |
Revert "um: allocate a guard page to helper threads"
This reverts commit ef4459a6da09 ("um: allocate a guard page to
helper threads"), it's broken in multiple ways:
1) the free no longer matches the alloc; and
2) more importantly, the set_memory_ro() causes allocation of
page tables for the normal memory that doesn't have any,
and that later causes corruption and crashes (usually but
not always in vfree()).
We could fix the first bug and use vmalloc() to work around the
second, but set_memory_ro() actually doesn't do anything either
so I'll just revert that as well.
Reported-by: Benjamin Berg <benjamin@sipsolutions.net>
Fixes: ef4459a6da09 ("um: allocate a guard page to helper threads")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Diffstat (limited to 'arch/um/kernel')
| -rw-r--r-- | arch/um/kernel/process.c | 11 |
1 files changed, 4 insertions, 7 deletions
diff --git a/arch/um/kernel/process.c b/arch/um/kernel/process.c index 2a986ece5478..81d508daf67c 100644 --- a/arch/um/kernel/process.c +++ b/arch/um/kernel/process.c @@ -32,7 +32,6 @@ #include <os.h> #include <skas.h> #include <linux/time-internal.h> -#include <asm/set_memory.h> /* * This is a per-cpu array. A processor only modifies its entry and it only @@ -63,18 +62,16 @@ void free_stack(unsigned long stack, int order) free_pages(stack, order); } -unsigned long alloc_stack(int atomic) +unsigned long alloc_stack(int order, int atomic) { - unsigned long addr; + unsigned long page; gfp_t flags = GFP_KERNEL; if (atomic) flags = GFP_ATOMIC; - addr = __get_free_pages(flags, 1); + page = __get_free_pages(flags, order); - set_memory_ro(addr, 1); - - return addr + PAGE_SIZE; + return page; } static inline void set_current(struct task_struct *task) |