| Message ID | 20230524152633.203927-2-deller@gmx.de (mailing list archive) |
|---|---|
| State | Accepted, archived |
| Headers | show |
| Series | Fix flush_dcache_page() for usage from irq context on ARM, NIOS2 and PARISC | expand |
On Wed, May 24, 2023, at 17:26, Helge Deller wrote: > 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 > 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) <linux@armlinux.org.uk> > Cc: Arnd Bergmann <arnd@arndb.de> > Cc: linux-arm-kernel@lists.infradead.org > Signed-off-by: Helge Deller <deller@gmx.de> Cc: stable@vger.kernel.org Reviewed-by: Arnd Bergmann <arnd@arndb.de> From what I can tell, the behavior in aio_complete has been there for over 10 years, since 21b40200cfe96 ("aio: use flush_dcache_page()"). Others may have done the same already back then. I also see you sent patches for nios2 and parisc, but not for csky, which appears to need the same thing. Arnd
On 5/24/23 22:00, Arnd Bergmann wrote: > On Wed, May 24, 2023, at 17:26, Helge Deller wrote: >> 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 >> 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) <linux@armlinux.org.uk> >> Cc: Arnd Bergmann <arnd@arndb.de> >> Cc: linux-arm-kernel@lists.infradead.org >> Signed-off-by: Helge Deller <deller@gmx.de> > > Cc: stable@vger.kernel.org > Reviewed-by: Arnd Bergmann <arnd@arndb.de> Thanks! I assume it's picked up in the arm git tree then. > From what I can tell, the behavior in aio_complete has been > there for over 10 years, since 21b40200cfe96 ("aio: use > flush_dcache_page()"). Oh, then those arches are broken since then. > Others may have done the same already back then. > > I also see you sent patches for nios2 and parisc, but not > for csky, which appears to need the same thing. csky doesn't use flush_dcache_mmap_lock() inside it's flush_dcache_page() function, so I think it's not affected. Helge
On 5/24/23 22:00, Arnd Bergmann wrote: > On Wed, May 24, 2023, at 17:26, Helge Deller wrote: >> 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 >> 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) <linux@armlinux.org.uk> >> Cc: Arnd Bergmann <arnd@arndb.de> >> Cc: linux-arm-kernel@lists.infradead.org >> Signed-off-by: Helge Deller <deller@gmx.de> > > Cc: stable@vger.kernel.org > Reviewed-by: Arnd Bergmann <arnd@arndb.de> > > From what I can tell, the behavior in aio_complete has been > there for over 10 years, since 21b40200cfe96 ("aio: use > flush_dcache_page()"). Others may have done the same already > back then. gentle ping... I think this patch hasn't been picked up yet for arm. Helge
diff --git a/arch/arm/include/asm/cacheflush.h b/arch/arm/include/asm/cacheflush.h index a094f964c869..5b8a1ef0dc50 100644 --- a/arch/arm/include/asm/cacheflush.h +++ b/arch/arm/include/asm/cacheflush.h @@ -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 diff --git a/arch/arm/mm/flush.c b/arch/arm/mm/flush.c index 7ff9feea13a6..d57ec9165520 100644 --- a/arch/arm/mm/flush.c +++ b/arch/arm/mm/flush.c @@ -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
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 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) <linux@armlinux.org.uk> Cc: Arnd Bergmann <arnd@arndb.de> Cc: linux-arm-kernel@lists.infradead.org Signed-off-by: Helge Deller <deller@gmx.de> --- arch/arm/include/asm/cacheflush.h | 4 ++++ arch/arm/mm/flush.c | 5 +++-- 2 files changed, 7 insertions(+), 2 deletions(-) -- 2.38.1