Skip to contentSkip to conversation

arm: Fix flush_dcache_page() for usage from irq context

PATCH RESEND Superseded Helge Deller 2 participants 2 messages Aug 18, 2023 – Aug 21, 2023 Arm (32-bit)

v1 of 2 Superseded Latest is v2 →

lore
Share & tools
lore

Helge Deller

author
#0 lore raw

PATCH RESEND 1/1 arm: Fix flush_dcache_page() for usage from irq context

Since at least kernel 6.1, flush_dcache_page() is called with IRQs disabled, e.g. from aio_complete().

But the current implementation for flush_dcache_page() on ARM (32-bit) 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.

Cc "Russell King (Oracle)" <[email protected]>
Cc Arnd Bergmann <[email protected]>
Cc [email protected]
Reviewed-by Arnd Bergmann <[email protected]>
Signed-off-by Helge Deller <[email protected]>

---

arch/arm/include/asm/cacheflush.h +4 -0
index a094f964c869..5b8a1ef0dc50 100644
@@ -315,6 +315,10 @@ static inline void flush_anon_page(struct vm_area_struct *vma,
 
 #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)
 
 /*
  * We don't appear to need to do anything here.  In fact, if we did, we'd
arch/arm/mm/flush.c +3 -2
index 2508be91b7a0..e70dd5e354ae 100644
@@ -238,6 +238,7 @@ static void __flush_dcache_aliases(struct address_space *mapping, struct page *p
 {
 	struct mm_struct *mm = current->active_mm;
 	struct vm_area_struct *mpnt;
+	unsigned long flags;
 	pgoff_t pgoff;
 
 	/*

@@ -248,7 +249,7 @@ static void __flush_dcache_aliases(struct address_space *mapping, struct page *p
 	 */
 	pgoff = page->index;
 
-	flush_dcache_mmap_lock(mapping);
+	flush_dcache_mmap_lock_irqsave(mapping, flags);
 	vma_interval_tree_foreach(mpnt, &mapping->i_mmap, pgoff, pgoff) {
 		unsigned long offset;
 

@@ -262,7 +263,7 @@ static void __flush_dcache_aliases(struct address_space *mapping, struct page *p
 		offset = (pgoff - mpnt->vm_pgoff) << PAGE_SHIFT;
 		flush_cache_page(mpnt, mpnt->vm_start + offset, page_to_pfn(page));
 	}
-	flush_dcache_mmap_unlock(mapping);
+	flush_dcache_mmap_unlock_irqrestore(mapping, flags);
 }
 
 #if __LINUX_ARM_ARCH__ >= 6

_______________________________________________
linux-arm-kernel mailing list
[email protected]
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

maintainer
#1 lore raw
Quoted 6 lines · Helge Deller

Since at least kernel 6.1, flush_dcache_page() is called with IRQs disabled, e.g. from aio_complete().

But the current implementation for flush_dcache_page() on ARM (32-bit) unintentionally re-enables IRQs, which may lead to deadlocks.

Quoted 8 lines

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

Cc "Russell King (Oracle)" <[email protected]>
Cc Arnd Bergmann <[email protected]>
Cc [email protected]
Reviewed-by Arnd Bergmann <[email protected]>
Signed-off-by Helge Deller <[email protected]>

Please submit to the patch system, details can be found in my email signature below.

Signature · 2 lines
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!