diff options
author | Nam Cao <namcao@linutronix.de> | 2024-05-15 08:50:40 +0300 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2024-06-21 15:40:35 +0300 |
commit | d5257ceb19d92069195254866421f425aea42915 (patch) | |
tree | bdbdd142079685a211d3fd0ba35b46b12b84948f /arch | |
parent | 8e21de5f99b2368a5155037ce0aae8aaba3f5241 (diff) | |
download | linux-d5257ceb19d92069195254866421f425aea42915.tar.xz |
riscv: rewrite __kernel_map_pages() to fix sleeping in invalid context
commit fb1cf0878328fe75d47f0aed0a65b30126fcefc4 upstream.
__kernel_map_pages() is a debug function which clears the valid bit in page
table entry for deallocated pages to detect illegal memory accesses to
freed pages.
This function set/clear the valid bit using __set_memory(). __set_memory()
acquires init_mm's semaphore, and this operation may sleep. This is
problematic, because __kernel_map_pages() can be called in atomic context,
and thus is illegal to sleep. An example warning that this causes:
BUG: sleeping function called from invalid context at kernel/locking/rwsem.c:1578
in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 2, name: kthreadd
preempt_count: 2, expected: 0
CPU: 0 PID: 2 Comm: kthreadd Not tainted 6.9.0-g1d4c6d784ef6 #37
Hardware name: riscv-virtio,qemu (DT)
Call Trace:
[<ffffffff800060dc>] dump_backtrace+0x1c/0x24
[<ffffffff8091ef6e>] show_stack+0x2c/0x38
[<ffffffff8092baf8>] dump_stack_lvl+0x5a/0x72
[<ffffffff8092bb24>] dump_stack+0x14/0x1c
[<ffffffff8003b7ac>] __might_resched+0x104/0x10e
[<ffffffff8003b7f4>] __might_sleep+0x3e/0x62
[<ffffffff8093276a>] down_write+0x20/0x72
[<ffffffff8000cf00>] __set_memory+0x82/0x2fa
[<ffffffff8000d324>] __kernel_map_pages+0x5a/0xd4
[<ffffffff80196cca>] __alloc_pages_bulk+0x3b2/0x43a
[<ffffffff8018ee82>] __vmalloc_node_range+0x196/0x6ba
[<ffffffff80011904>] copy_process+0x72c/0x17ec
[<ffffffff80012ab4>] kernel_clone+0x60/0x2fe
[<ffffffff80012f62>] kernel_thread+0x82/0xa0
[<ffffffff8003552c>] kthreadd+0x14a/0x1be
[<ffffffff809357de>] ret_from_fork+0xe/0x1c
Rewrite this function with apply_to_existing_page_range(). It is fine to
not have any locking, because __kernel_map_pages() works with pages being
allocated/deallocated and those pages are not changed by anyone else in the
meantime.
Fixes: 5fde3db5eb02 ("riscv: add ARCH_SUPPORTS_DEBUG_PAGEALLOC support")
Signed-off-by: Nam Cao <namcao@linutronix.de>
Cc: stable@vger.kernel.org
Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Link: https://lore.kernel.org/r/1289ecba9606a19917bc12b6c27da8aa23e1e5ae.1715750938.git.namcao@linutronix.de
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch')
-rw-r--r-- | arch/riscv/mm/pageattr.c | 28 |
1 files changed, 22 insertions, 6 deletions
diff --git a/arch/riscv/mm/pageattr.c b/arch/riscv/mm/pageattr.c index 410056a50aa9..271d01a5ba4d 100644 --- a/arch/riscv/mm/pageattr.c +++ b/arch/riscv/mm/pageattr.c @@ -387,17 +387,33 @@ int set_direct_map_default_noflush(struct page *page) } #ifdef CONFIG_DEBUG_PAGEALLOC +static int debug_pagealloc_set_page(pte_t *pte, unsigned long addr, void *data) +{ + int enable = *(int *)data; + + unsigned long val = pte_val(ptep_get(pte)); + + if (enable) + val |= _PAGE_PRESENT; + else + val &= ~_PAGE_PRESENT; + + set_pte(pte, __pte(val)); + + return 0; +} + void __kernel_map_pages(struct page *page, int numpages, int enable) { if (!debug_pagealloc_enabled()) return; - if (enable) - __set_memory((unsigned long)page_address(page), numpages, - __pgprot(_PAGE_PRESENT), __pgprot(0)); - else - __set_memory((unsigned long)page_address(page), numpages, - __pgprot(0), __pgprot(_PAGE_PRESENT)); + unsigned long start = (unsigned long)page_address(page); + unsigned long size = PAGE_SIZE * numpages; + + apply_to_existing_page_range(&init_mm, start, size, debug_pagealloc_set_page, &enable); + + flush_tlb_kernel_range(start, start + size); } #endif |