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Without CONFIG_DEBUG_VM=3Dy, VM_WARN_ON(!put_page_testzero(pfn_= to_page(pfn))) >>>> and is_check_pages_enabled(), which leads to free_page_is_bad()=E2=80= =99s >>>> =E2=80=9Cpage dumped because: nonzero _refcount=E2=80=9D, are disabled= . >>>> >>>> It seems to me that someone else bump the page refcount between >>>> VM_WARN_ON(!put_page_testzero(pfn_to_page(pfn))) and free_page_is_bad(= ). >>>> >>> >>> Merging Ron=E2=80=99s reply from another thread[1]: >>> >>> =E2=80=9CSomething strange is going on. I enabled CONFIG_DEBUG_VM by it= self and >>> the issue went away. Let me try CONFIG_DEBUG_PAGE_REF.=E2=80=9D >>> >>> Looks like something is racy, since it is reproducible reliably. >>> >>> [1] https://lore.kernel.org/all/30dd1efc-9bd9-4664-999e-610d181600f9@w6= rz.net/ >> >> VM_WARN_ON() is BUILD_BUG_ON_INVALID() when CONFIG_DEBUG_VM is off. Only >> the validity of the expression is checked and no code is generated. >> So that put_page_testzero() becomes a NOP. > > Indeed... > >> >> Hi Ron, >> >> Can you check if the patch below fix the issue without CONFIG_DEBUG_VM? >> >> diff --git a/mm/cma.c b/mm/cma.c >> index 94b5da468a7d..96be62eb3713 100644 >> --- a/mm/cma.c >> +++ b/mm/cma.c >> @@ -1020,8 +1020,11 @@ bool cma_release(struct cma *cma, const struct pa= ge *pages, >> return false; >> >> pfn =3D page_to_pfn(pages); >> - for (i =3D 0; i < count; i++, pfn++) >> - VM_WARN_ON(!put_page_testzero(pfn_to_page(pfn))); >> + for (i =3D 0; i < count; i++, pfn++) { >> + int __maybe_unused ret =3D put_page_testzero(pfn_to_page(pfn)); >> + >> + VM_WARN_ON(!ret); >> + } > > Maybe we only warn once by adding back the original check? > > diff --git a/mm/cma.c b/mm/cma.c > index 94b5da468a7d..a73a22d34232 100644 > --- a/mm/cma.c > +++ b/mm/cma.c > @@ -1014,14 +1014,17 @@ bool cma_release(struct cma *cma, const struct pa= ge *pages, > { > struct cma_memrange *cmr; > unsigned long i, pfn; > + int ret =3D 0; > > cmr =3D find_cma_memrange(cma, pages, count); > if (!cmr) > return false; > > pfn =3D page_to_pfn(pages); > - for (i =3D 0; i < count; i++, pfn++) > - VM_WARN_ON(!put_page_testzero(pfn_to_page(pfn))); > + for (i =3D 0; i < count; i++, pfn++) { > + ret + =3D put_page_testzero(pfn_to_page(pfn)); > + > + WARN(ret !=3D 0, "%lu pages are still in use!\n", ret); > > __cma_release_frozen(cma, cmr, pages, count); Sounds like a better solution. Let me use this as v2 fix. Thanks. > > > >> >> __cma_release_frozen(cma, cmr, pages, count); >> >> >> >> Best Regards, >> Yan, Zi >> Best Regards, Yan, Zi