Re: [PATCH 2/3] mm/mmu_notifier: use structure for invalidate_range_start/end calls
flat view
From: Jan Kara <jack@suse.cz>
Date: 2018-12-05 11:04:16
Also in:
dri-devel, kvm, linux-fsdevel, linux-mm, lkml
Hi Jerome! On Mon 03-12-18 15:18:16, jglisse@redhat.com wrote:
From: Jérôme Glisse <redacted> To avoid having to change many call sites everytime we want to add a parameter use a structure to group all parameters for the mmu_notifier invalidate_range_start/end cakks. No functional changes with this patch.
Two suggestions for the patch below:
quoted hunk ↗ jump to hunk
@@ -772,7 +775,8 @@ static void dax_entry_mkclean(struct address_space *mapping, pgoff_t index, * call mmu_notifier_invalidate_range_start() on our behalf * before taking any lock. */ - if (follow_pte_pmd(vma->vm_mm, address, &start, &end, &ptep, &pmdp, &ptl)) + if (follow_pte_pmd(vma->vm_mm, address, &range, + &ptep, &pmdp, &ptl)) continue;
The change of follow_pte_pmd() arguments looks unexpected. Why should that care about mmu notifier range? I see it may be convenient but it doesn't look like a good API to me.
quoted hunk ↗ jump to hunk
@@ -1139,11 +1140,15 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf, downgrade_write(&mm->mmap_sem); break; } - mmu_notifier_invalidate_range_start(mm, 0, -1); + + range.start = 0; + range.end = -1UL; + range.mm = mm; + mmu_notifier_invalidate_range_start(&range);
Also how about providing initializer for struct mmu_notifier_range? Or something like DECLARE_MMU_NOTIFIER_RANGE? That will make sure that unused arguments for particular notification places have defined values and also if you add another mandatory argument (like you do in your third patch), you just add another argument to the initializer and that way the compiler makes sure you haven't missed any place. Finally the code will remain more compact that way (less lines needed to initialize the struct). Honza -- Jan Kara [off-list ref] SUSE Labs, CR _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel