Dear stable kernel team,

could you please add the patch below to all stable kernels from v4.19 up to 5.15.

It's a manual backport of upstream commit 61e150fb310729c98227a5edf6e4a3619edc3702, which doesn't applies cleanly otherwise.

Thanks! Helge

From 97d6d8f6248364ec916e9642a58f1ed14a1eb147 Mon Sep 17 00:00:00 2001 From: Helge Deller deller@gmx.de Date: Fri, 26 May 2023 22:51:07 +0200 Subject: [PATCH] parisc: Fix flush_dcache_page() for usage from irq context

flush_dcache_page() may be called with IRQs disabled.

But the current implementation for flush_dcache_page() on parisc unintentionally re-enables IRQs, which may lead to deadlocks.

Fix it by using xa_lock_irqsave() and xa_unlock_irqrestore() for the flush_dcache_mmap_*lock() macros instead.

Signed-off-by: Helge Deller deller@gmx.de --- arch/parisc/include/asm/cacheflush.h | 5 +++++ arch/parisc/kernel/cache.c | 5 +++-- 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/arch/parisc/include/asm/cacheflush.h b/arch/parisc/include/asm/cacheflush.h index eef0096db5f8..2f4c45f60ae1 100644 --- a/arch/parisc/include/asm/cacheflush.h +++ b/arch/parisc/include/asm/cacheflush.h @@ -53,6 +53,11 @@ extern void flush_dcache_page(struct page *page);

#define flush_dcache_mmap_lock(mapping) xa_lock_irq(&mapping->i_pages) #define flush_dcache_mmap_unlock(mapping) xa_unlock_irq(&mapping->i_pages) +#define flush_dcache_mmap_lock_irqsave(mapping, flags) \ + xa_lock_irqsave(&mapping->i_pages, flags) +#define flush_dcache_mmap_unlock_irqrestore(mapping, flags) \ + xa_unlock_irqrestore(&mapping->i_pages, flags) +

#define flush_icache_page(vma,page) do { \ flush_kernel_dcache_page_addr(page_address(page)); \ diff --git a/arch/parisc/kernel/cache.c b/arch/parisc/kernel/cache.c index 394e6e14e5c4..c473c2f395a0 100644 --- a/arch/parisc/kernel/cache.c +++ b/arch/parisc/kernel/cache.c @@ -324,6 +324,7 @@ void flush_dcache_page(struct page *page) struct vm_area_struct *mpnt; unsigned long offset; unsigned long addr, old_addr = 0; + unsigned long flags; pgoff_t pgoff;

if (mapping && !mapping_mapped(mapping)) { @@ -343,7 +344,7 @@ void flush_dcache_page(struct page *page) * declared as MAP_PRIVATE or MAP_SHARED), so we only need * to flush one address here for them all to become coherent */

- flush_dcache_mmap_lock(mapping); + flush_dcache_mmap_lock_irqsave(mapping, flags); vma_interval_tree_foreach(mpnt, &mapping->i_mmap, pgoff, pgoff) { offset = (pgoff - mpnt->vm_pgoff) << PAGE_SHIFT; addr = mpnt->vm_start + offset; @@ -366,7 +367,7 @@ void flush_dcache_page(struct page *page) old_addr = addr; } } - flush_dcache_mmap_unlock(mapping); + flush_dcache_mmap_unlock_irqrestore(mapping, flags); } EXPORT_SYMBOL(flush_dcache_page);

-- 2.38.1