FAILED: patch "[PATCH] riscv: rewrite __kernel_map_pages() to fix sleeping in" failed to apply to 5.10-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 5.10-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.10.y
git checkout FETCH_HEAD
git cherry-pick -x fb1cf0878328fe75d47f0aed0a65b30126fcefc4
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2024061927-remindful-dash-9f14@gregkh' --subject-prefix 'PATCH 5.10.y' HEAD^..

Possible dependencies:

fb1cf0878328 ("riscv: rewrite __kernel_map_pages() to fix sleeping in invalid context")
5d6ad668f316 ("arch, mm: restore dependency of __kernel_map_pages() on DEBUG_PAGEALLOC")
2abf962a8d42 ("PM: hibernate: make direct map manipulations more explicit")
77bc7fd607de ("mm: introduce debug_pagealloc_{map,unmap}_pages() helpers")
4f5b0c178996 ("arm, arm64: move free_unused_memmap() to generic mm")
5e545df3292f ("arm: remove CONFIG_ARCH_HAS_HOLES_MEMORYMODEL")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From fb1cf0878328fe75d47f0aed0a65b30126fcefc4 Mon Sep 17 00:00:00 2001
From: Nam Cao <namcao@linutronix.de>
Date: Wed, 15 May 2024 07:50:40 +0200
Subject: [PATCH] riscv: rewrite __kernel_map_pages() to fix sleeping in
 invalid context

__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>

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