On Tue, Jan 7, 2025 at 10:50 AM Liam R. Howlett <Liam.Howlett@xxxxxxxxxx> wrote: > > * Suren Baghdasaryan <surenb@xxxxxxxxxx> [241226 15:03]: > > vma->vm_refcnt does not exist when CONFIG_PER_VMA_LOCK=n, therefore > > when CONFIG_PER_VMA_LOCK=n and CONFIG_DEBUG_VM=y we need to avoid its > > usage in dump_vma(). > > It might be worth having a function that decodes the information in the > vma lock and outputs a string that spells out what is going on, You mean something like "attached, 2 reader(s), 0 writer(s)" instead of "refcnt 0x3" ? > and > another that just outputs "not supported" or something. Do you mean we should report "not supported" when CONFIG_PER_VMA_LOCK=n? > > This has the benefit of spelling out the state and only having one place > to update in future dump_vma() changes. > > > > > Reported-by: kernel test robot <lkp@xxxxxxxxx> > > Closes: https://lore.kernel.org/oe-kbuild-all/202412270328.HiJX1mRt-lkp@xxxxxxxxx/ > > Signed-off-by: Suren Baghdasaryan <surenb@xxxxxxxxxx> > > --- > > Fixes https://lore.kernel.org/all/20241226170710.1159679-14-surenb@xxxxxxxxxx/ > > posted over mm-unstable. > > > > mm/debug.c | 12 ++++++++++++ > > 1 file changed, 12 insertions(+) > > > > diff --git a/mm/debug.c b/mm/debug.c > > index 68b3ba3cf603..9c4cbc3733b0 100644 > > --- a/mm/debug.c > > +++ b/mm/debug.c > > @@ -178,6 +178,7 @@ EXPORT_SYMBOL(dump_page); > > > > void dump_vma(const struct vm_area_struct *vma) > > { > > +#ifdef CONFIG_PER_VMA_LOCK > > pr_emerg("vma %px start %px end %px mm %px\n" > > "prot %lx anon_vma %px vm_ops %px\n" > > "pgoff %lx file %px private_data %px\n" > > @@ -187,6 +188,17 @@ void dump_vma(const struct vm_area_struct *vma) > > vma->anon_vma, vma->vm_ops, vma->vm_pgoff, > > vma->vm_file, vma->vm_private_data, > > vma->vm_flags, &vma->vm_flags, refcount_read(&vma->vm_refcnt)); > > +#else > > + pr_emerg("vma %px start %px end %px mm %px\n" > > + "prot %lx anon_vma %px vm_ops %px\n" > > + "pgoff %lx file %px private_data %px\n" > > + "flags: %#lx(%pGv)\n", > > + vma, (void *)vma->vm_start, (void *)vma->vm_end, vma->vm_mm, > > + (unsigned long)pgprot_val(vma->vm_page_prot), > > + vma->anon_vma, vma->vm_ops, vma->vm_pgoff, > > + vma->vm_file, vma->vm_private_data, > > + vma->vm_flags, &vma->vm_flags); > > +#endif > > } > > EXPORT_SYMBOL(dump_vma); > > > > -- > > 2.47.1.613.gc27f4b7a9f-goog > >
