Date: Thu, 03 Nov 2011 12:51:10 -0500 From: Alan Cox <alc@rice.edu> To: Kostik Belousov <kostikbel@gmail.com> Cc: "K. Macy" <kmacy@freebsd.org>, freebsd-current@freebsd.org, Penta Upa <bsdboot@gmail.com>, Andriy Gapon <avg@freebsd.org>, Benjamin Kaduk <kaduk@mit.edu> Subject: Re: panic at vm_page_wire with FreeBSD 9.0 Beta 3 Message-ID: <4EB2D48E.1030102@rice.edu> In-Reply-To: <20111103132437.GV50300@deviant.kiev.zoral.com.ua> References: <CAMsyT5QgHLqgSrt7qU_4FOVocW_GwmVWgZQ1A_CNrzkHQRTm4w@mail.gmail.com> <CAHM0Q_OWrQS_gnwupdJDwRFV9M3dKRN-SzkHgz6gJEedkvTPKQ@mail.gmail.com> <CAMsyT5Q5kMHRJQqFUdCCqqvKvFS_i5bvR8sHW6vNti_boD0nfA@mail.gmail.com> <alpine.GSO.1.10.1111020203230.882@multics.mit.edu> <4EB11C32.80106@FreeBSD.org> <4EB22938.4050803@rice.edu> <20111103132437.GV50300@deviant.kiev.zoral.com.ua>
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On 11/03/2011 08:24, Kostik Belousov wrote:
> On Thu, Nov 03, 2011 at 12:40:08AM -0500, Alan Cox wrote:
>> On 11/02/2011 05:32, Andriy Gapon wrote:
>>> [restored cc: to the original poster]
>>> As Bruce Evans has pointed to me privately [I am not sure why privately],
>>> there
>>> is already an example in i386 and amd64 atomic.h, where operations are
>>> inlined
>>> for a kernel build, but presented as real (external) functions for a module
>>> build. You can search e.g. sys/amd64/include/atomic.h for KLD_MODULE.
>>>
>>> I think that the same treatment could/should be applied to vm_page_*lock*
>>> operations defined in sys/vm/vm_page.h.
>> *snip*
>>
>> Yes, it should be. There are without question legitimate reasons for a
>> module to acquire a page lock.
> I agree. Also, I think that we should use the opportunity to also isolate
> the modules from the struct vm_page layout changes. As example, I converted
> nfsclient.ko.
>
I would suggest introducing the vm_page_bits_t change first. If, at the
same time, you change the return type from the function vm_page_bits()
to use vm_page_bits_t, then I believe it is straightforward to fix all
of the places in vm_page.c that don't properly handle a 32 KB page size.
Alan
> Patch is not tested.
>
> diff --git a/sys/nfsclient/nfs_bio.c b/sys/nfsclient/nfs_bio.c
> index 305c189..7264cd1 100644
> --- a/sys/nfsclient/nfs_bio.c
> +++ b/sys/nfsclient/nfs_bio.c
> @@ -128,7 +128,7 @@ nfs_getpages(struct vop_getpages_args *ap)
> * can only occur at the file EOF.
> */
> VM_OBJECT_LOCK(object);
> - if (pages[ap->a_reqpage]->valid != 0) {
> + if (vm_page_read_valid(pages[ap->a_reqpage]) != 0) {
> for (i = 0; i< npages; ++i) {
> if (i != ap->a_reqpage) {
> vm_page_lock(pages[i]);
> @@ -198,16 +198,16 @@ nfs_getpages(struct vop_getpages_args *ap)
> /*
> * Read operation filled an entire page
> */
> - m->valid = VM_PAGE_BITS_ALL;
> - KASSERT(m->dirty == 0,
> + vm_page_write_valid(m, VM_PAGE_BITS_ALL);
> + KASSERT(vm_page_read_dirty(m) == 0,
> ("nfs_getpages: page %p is dirty", m));
> } else if (size> toff) {
> /*
> * Read operation filled a partial page.
> */
> - m->valid = 0;
> + vm_page_write_valid(m, 0);
> vm_page_set_valid(m, 0, size - toff);
> - KASSERT(m->dirty == 0,
> + KASSERT(vm_page_read_dirty(m) == 0,
> ("nfs_getpages: page %p is dirty", m));
> } else {
> /*
> diff --git a/sys/vm/vm_page.c b/sys/vm/vm_page.c
> index f14da4a..5b8b4e3 100644
> --- a/sys/vm/vm_page.c
> +++ b/sys/vm/vm_page.c
> @@ -2677,6 +2677,66 @@ vm_page_test_dirty(vm_page_t m)
> vm_page_dirty(m);
> }
>
> +void
> +vm_page_lock_func(vm_page_t m, const char *file, int line)
> +{
> +
> +#if LOCK_DEBUG> 0 || defined(MUTEX_NOINLINE)
> + _mtx_lock_flags(vm_page_lockptr(m), 0, file, line);
> +#else
> + __mtx_lock(vm_page_lockptr(m), 0, file, line);
> +#endif
> +}
> +
> +void
> +vm_page_unlock_func(vm_page_t m, const char *file, int line)
> +{
> +
> +#if LOCK_DEBUG> 0 || defined(MUTEX_NOINLINE)
> + _mtx_unlock_flags(vm_page_lockptr(m), 0, file, line);
> +#else
> + __mtx_unlock(vm_page_lockptr(m), curthread, 0, file, line);
> +#endif
> +}
> +
> +int
> +vm_page_trylock_func(vm_page_t m, const char *file, int line)
> +{
> +
> + return (_mtx_trylock(vm_page_lockptr(m), 0, file, line));
> +}
> +
> +void
> +vm_page_lock_assert_func(vm_page_t m, int a, const char *file, int line)
> +{
> +
> +#ifdef INVARIANTS
> + _mtx_assert(vm_page_lockptr(m), a, file, line);
> +#endif
> +}
> +
> +vm_page_bits_t
> +vm_page_read_dirty_func(vm_page_t m)
> +{
> +
> + return (m->dirty);
> +}
> +
> +vm_page_bits_t
> +vm_page_read_valid_func(vm_page_t m)
> +{
> +
> + return (m->valid);
> +}
> +
> +void
> +vm_page_write_valid_func(vm_page_t m, vm_page_bits_t v)
> +{
> +
> + m->valid = v;
> +}
> +
> +
> int so_zerocp_fullpage = 0;
>
> /*
> diff --git a/sys/vm/vm_page.h b/sys/vm/vm_page.h
> index 23637bb..618ba2b 100644
> --- a/sys/vm/vm_page.h
> +++ b/sys/vm/vm_page.h
> @@ -113,6 +113,21 @@
>
> TAILQ_HEAD(pglist, vm_page);
>
> +#if PAGE_SIZE == 4096
> +#define VM_PAGE_BITS_ALL 0xffu
> +typedef uint8_t vm_page_bits_t;
> +#elif PAGE_SIZE == 8192
> +#define VM_PAGE_BITS_ALL 0xffffu
> +typedef uint16_t vm_page_bits_t;
> +#elif PAGE_SIZE == 16384
> +#define VM_PAGE_BITS_ALL 0xffffffffu
> +typedef uint32_t vm_page_bits_t;
> +#elif PAGE_SIZE == 32768
> +#define VM_PAGE_BITS_ALL 0xfffffffffffffffflu
> +typedef uint64_t vm_page_bits_t;
> +#endif
> +
> +
> struct vm_page {
> TAILQ_ENTRY(vm_page) pageq; /* queue info for FIFO queue or free list (Q) */
> TAILQ_ENTRY(vm_page) listq; /* pages in same object (O) */
> @@ -138,19 +153,8 @@ struct vm_page {
> /* NOTE that these must support one bit per DEV_BSIZE in a page!!! */
> /* so, on normal X86 kernels, they must be at least 8 bits wide */
> /* In reality, support for 32KB pages is not fully implemented. */
> -#if PAGE_SIZE == 4096
> - uint8_t valid; /* map of valid DEV_BSIZE chunks (O) */
> - uint8_t dirty; /* map of dirty DEV_BSIZE chunks (M) */
> -#elif PAGE_SIZE == 8192
> - uint16_t valid; /* map of valid DEV_BSIZE chunks (O) */
> - uint16_t dirty; /* map of dirty DEV_BSIZE chunks (M) */
> -#elif PAGE_SIZE == 16384
> - uint32_t valid; /* map of valid DEV_BSIZE chunks (O) */
> - uint32_t dirty; /* map of dirty DEV_BSIZE chunks (M) */
> -#elif PAGE_SIZE == 32768
> - uint64_t valid; /* map of valid DEV_BSIZE chunks (O) */
> - uint64_t dirty; /* map of dirty DEV_BSIZE chunks (M) */
> -#endif
> + vm_page_bits_t valid; /* map of valid DEV_BSIZE chunks (O) */
> + vm_page_bits_t dirty; /* map of dirty DEV_BSIZE chunks (M) */
> };
>
> /*
> @@ -216,12 +220,50 @@ extern struct vpglocks pa_lock[];
>
> #define PA_LOCK_ASSERT(pa, a) mtx_assert(PA_LOCKPTR(pa), (a))
>
> +#ifdef KLD_MODULE
> +#define vm_page_lock(m) vm_page_lock_func((m), LOCK_FILE, LOCK_LINE)
> +#define vm_page_unlock(m) vm_page_unlock_func((m), LOCK_FILE, LOCK_LINE)
> +#define vm_page_trylock(m) vm_page_trylock_func((m), LOCK_FILE, LOCK_LINE)
> +#ifdef INVARIANTS
> +#define vm_page_lock_assert(m, a) \
> + vm_page_lock_assert_func((m), (a), LOCK_FILE, LOCK_LINE)
> +#else
> +#define vm_page_lock_assert(m, a)
> +#endif
> +
> +#define vm_page_read_dirty(m) vm_page_read_dirty_func((m))
> +#define vm_page_read_valid(m) vm_page_read_valid_func((m))
> +#define vm_page_write_valid(m, v) vm_page_write_valid_func((m), (v))
> +
> +#else /* KLD_MODULE */
> #define vm_page_lockptr(m) (PA_LOCKPTR(VM_PAGE_TO_PHYS((m))))
> #define vm_page_lock(m) mtx_lock(vm_page_lockptr((m)))
> #define vm_page_unlock(m) mtx_unlock(vm_page_lockptr((m)))
> #define vm_page_trylock(m) mtx_trylock(vm_page_lockptr((m)))
> #define vm_page_lock_assert(m, a) mtx_assert(vm_page_lockptr((m)), (a))
>
> +static inline vm_page_bits_t
> +vm_page_read_dirty(vm_page_t m)
> +{
> +
> + return (m->dirty);
> +}
> +
> +static inline vm_page_bits_t
> +vm_page_read_valid(vm_page_t m)
> +{
> +
> + return (m->valid);
> +}
> +
> +static inline void
> +vm_page_write_valid(vm_page_t m, vm_page_bits_t v)
> +{
> +
> + m->valid = v;
> +}
> +#endif
> +
> #define vm_page_queue_free_mtx vm_page_queue_free_lock.data
> /*
> * These are the flags defined for vm_page.
> @@ -322,16 +364,6 @@ extern struct vpglocks vm_page_queue_lock;
> #define vm_page_lock_queues() mtx_lock(&vm_page_queue_mtx)
> #define vm_page_unlock_queues() mtx_unlock(&vm_page_queue_mtx)
>
> -#if PAGE_SIZE == 4096
> -#define VM_PAGE_BITS_ALL 0xffu
> -#elif PAGE_SIZE == 8192
> -#define VM_PAGE_BITS_ALL 0xffffu
> -#elif PAGE_SIZE == 16384
> -#define VM_PAGE_BITS_ALL 0xffffffffu
> -#elif PAGE_SIZE == 32768
> -#define VM_PAGE_BITS_ALL 0xfffffffffffffffflu
> -#endif
> -
> /* page allocation classes: */
> #define VM_ALLOC_NORMAL 0
> #define VM_ALLOC_INTERRUPT 1
> @@ -411,6 +443,15 @@ void vm_page_cowfault (vm_page_t);
> int vm_page_cowsetup(vm_page_t);
> void vm_page_cowclear (vm_page_t);
>
> +void vm_page_lock_func(vm_page_t m, const char *file, int line);
> +void vm_page_unlock_func(vm_page_t m, const char *file, int line);
> +int vm_page_trylock_func(vm_page_t m, const char *file, int line);
> +void vm_page_lock_assert_func(vm_page_t m, int a, const char *file, int line);
> +
> +vm_page_bits_t vm_page_read_dirty_func(vm_page_t m);
> +vm_page_bits_t vm_page_read_valid_func(vm_page_t m);
> +void vm_page_write_valid_func(vm_page_t m, vm_page_bits_t v);
> +
> #ifdef INVARIANTS
> void vm_page_object_lock_assert(vm_page_t m);
> #define VM_PAGE_OBJECT_LOCK_ASSERT(m) vm_page_object_lock_assert(m)
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