git: 14dcd4098374 - main - linuxkpi: `GFP_KERNEL` equals `M_NOWAIT` now
Date: Fri, 24 Nov 2023 17:31:54 UTC
The branch main has been updated by dumbbell:
URL: https://cgit.FreeBSD.org/src/commit/?id=14dcd40983748596d116d91acb934a8a95ac76bc
commit 14dcd40983748596d116d91acb934a8a95ac76bc
Author: Jean-Sébastien Pédron <dumbbell@FreeBSD.org>
AuthorDate: 2023-11-24 17:30:33 +0000
Commit: Jean-Sébastien Pédron <dumbbell@FreeBSD.org>
CommitDate: 2023-11-24 17:31:32 +0000
linuxkpi: `GFP_KERNEL` equals `M_NOWAIT` now
... instead of `M_WAITOK`.
[Why]
The reason is that in some places in the DRM drivers (in particular, the
framebuffer management code), kmalloc() is called from a non-sleepable
context, such as after a call to mtx_lock(8) with an MTX_DEF mutex.
If `GFP_KERNEL` is defined as `M_WAITOK`, we hit an assertion from
witness(4).
[How]
The definition of `GFP_KERNEL` is changed to `M_NOWAIT`. This means that
callers should verify the return value of kmalloc(). Fortunately, this
is always the case in Linux.
Reviewed by: bz, emaste, manu
Approved by: manu
Differential Revision: https://reviews.freebsd.org/D42054
---
sys/compat/linuxkpi/common/include/linux/gfp.h | 2 +-
sys/compat/linuxkpi/common/include/linux/slab.h | 8 ++++----
sys/compat/linuxkpi/common/src/linux_compat.c | 7 +++++--
sys/compat/linuxkpi/common/src/linux_interrupt.c | 3 +++
sys/compat/linuxkpi/common/src/linux_pci.c | 4 ++--
sys/compat/linuxkpi/common/src/linux_shmemfs.c | 11 +++++++++--
6 files changed, 24 insertions(+), 11 deletions(-)
diff --git a/sys/compat/linuxkpi/common/include/linux/gfp.h b/sys/compat/linuxkpi/common/include/linux/gfp.h
index c5de09e896de..17590806343f 100644
--- a/sys/compat/linuxkpi/common/include/linux/gfp.h
+++ b/sys/compat/linuxkpi/common/include/linux/gfp.h
@@ -64,7 +64,7 @@
#define GFP_NOWAIT M_NOWAIT
#define GFP_ATOMIC (M_NOWAIT | M_USE_RESERVE)
-#define GFP_KERNEL M_WAITOK
+#define GFP_KERNEL M_NOWAIT
#define GFP_USER M_WAITOK
#define GFP_HIGHUSER M_WAITOK
#define GFP_HIGHUSER_MOVABLE M_WAITOK
diff --git a/sys/compat/linuxkpi/common/include/linux/slab.h b/sys/compat/linuxkpi/common/include/linux/slab.h
index 8557f831bb60..3e857a4adc54 100644
--- a/sys/compat/linuxkpi/common/include/linux/slab.h
+++ b/sys/compat/linuxkpi/common/include/linux/slab.h
@@ -47,12 +47,12 @@ MALLOC_DECLARE(M_KMALLOC);
#define kzalloc(size, flags) kmalloc(size, (flags) | __GFP_ZERO)
#define kzalloc_node(size, flags, node) kmalloc_node(size, (flags) | __GFP_ZERO, node)
#define kfree_const(ptr) kfree(ptr)
-#define vzalloc(size) __vmalloc(size, GFP_KERNEL | __GFP_NOWARN | __GFP_ZERO, 0)
+#define vzalloc(size) __vmalloc(size, M_WAITOK | __GFP_NOWARN | __GFP_ZERO, 0)
#define vfree(arg) kfree(arg)
#define kvfree(arg) kfree(arg)
-#define vmalloc_node(size, node) __vmalloc_node(size, GFP_KERNEL, node)
-#define vmalloc_user(size) __vmalloc(size, GFP_KERNEL | __GFP_ZERO, 0)
-#define vmalloc(size) __vmalloc(size, GFP_KERNEL, 0)
+#define vmalloc_node(size, node) __vmalloc_node(size, M_WAITOK, node)
+#define vmalloc_user(size) __vmalloc(size, M_WAITOK | __GFP_ZERO, 0)
+#define vmalloc(size) __vmalloc(size, M_WAITOK, 0)
#define __kmalloc(...) kmalloc(__VA_ARGS__)
/*
diff --git a/sys/compat/linuxkpi/common/src/linux_compat.c b/sys/compat/linuxkpi/common/src/linux_compat.c
index b913ae602ab3..baa4ff2fee44 100644
--- a/sys/compat/linuxkpi/common/src/linux_compat.c
+++ b/sys/compat/linuxkpi/common/src/linux_compat.c
@@ -574,7 +574,7 @@ linux_file_alloc(void)
{
struct linux_file *filp;
- filp = kzalloc(sizeof(*filp), GFP_KERNEL);
+ filp = kzalloc(sizeof(*filp), M_WAITOK);
/* set initial refcount */
filp->f_count = 1;
@@ -1412,6 +1412,9 @@ linux_file_mmap_single(struct file *fp, const struct file_operations *fop,
return (EINVAL);
vmap = kzalloc(sizeof(*vmap), GFP_KERNEL);
+ if (vmap == NULL)
+ return (ENOMEM);
+
vmap->vm_start = 0;
vmap->vm_end = size;
vmap->vm_pgoff = *offset / PAGE_SIZE;
@@ -1941,7 +1944,7 @@ vmmap_add(void *addr, unsigned long size)
{
struct vmmap *vmmap;
- vmmap = kmalloc(sizeof(*vmmap), GFP_KERNEL);
+ vmmap = kmalloc(sizeof(*vmmap), M_WAITOK);
mtx_lock(&vmmaplock);
vmmap->vm_size = size;
vmmap->vm_addr = addr;
diff --git a/sys/compat/linuxkpi/common/src/linux_interrupt.c b/sys/compat/linuxkpi/common/src/linux_interrupt.c
index 5602b09c8fb8..886a5d5ad014 100644
--- a/sys/compat/linuxkpi/common/src/linux_interrupt.c
+++ b/sys/compat/linuxkpi/common/src/linux_interrupt.c
@@ -135,6 +135,9 @@ lkpi_request_irq(struct device *xdev, unsigned int irq,
GFP_KERNEL | __GFP_ZERO);
else
irqe = kzalloc(sizeof(*irqe), GFP_KERNEL);
+ if (irqe == NULL)
+ return (-ENOMEM);
+
irqe->dev = dev;
irqe->res = res;
irqe->arg = arg;
diff --git a/sys/compat/linuxkpi/common/src/linux_pci.c b/sys/compat/linuxkpi/common/src/linux_pci.c
index 8386552dcd51..f692b9c3ef09 100644
--- a/sys/compat/linuxkpi/common/src/linux_pci.c
+++ b/sys/compat/linuxkpi/common/src/linux_pci.c
@@ -305,7 +305,7 @@ lkpifill_pci_dev(device_t dev, struct pci_dev *pdev)
pdev->subsystem_device = pci_get_subdevice(dev);
pdev->class = pci_get_class(dev);
pdev->revision = pci_get_revid(dev);
- pdev->path_name = kasprintf(GFP_KERNEL, "%04d:%02d:%02d.%d",
+ pdev->path_name = kasprintf(M_WAITOK, "%04d:%02d:%02d.%d",
pci_get_domain(dev), pci_get_bus(dev), pci_get_slot(dev),
pci_get_function(dev));
pdev->bus = malloc(sizeof(*pdev->bus), M_DEVBUF, M_WAITOK | M_ZERO);
@@ -1469,7 +1469,7 @@ linux_dma_pool_create(char *name, struct device *dev, size_t size,
priv = dev->dma_priv;
- pool = kzalloc(sizeof(*pool), GFP_KERNEL);
+ pool = kzalloc(sizeof(*pool), M_WAITOK);
pool->pool_device = dev;
pool->pool_entry_size = size;
diff --git a/sys/compat/linuxkpi/common/src/linux_shmemfs.c b/sys/compat/linuxkpi/common/src/linux_shmemfs.c
index 3c71d6495f4a..bf6a8cd775e9 100644
--- a/sys/compat/linuxkpi/common/src/linux_shmemfs.c
+++ b/sys/compat/linuxkpi/common/src/linux_shmemfs.c
@@ -48,8 +48,15 @@ linux_shmem_read_mapping_page_gfp(vm_object_t obj, int pindex, gfp_t gfp)
struct page *page;
int rv;
- if ((gfp & GFP_NOWAIT) != 0)
- panic("GFP_NOWAIT is unimplemented");
+ /*
+ * Historically, GFP_KERNEL was the equivalent of M_WAITOK. But it was
+ * changed to a synonym of M_NOWAIT to allow allocations in
+ * non-sleepable code.
+ *
+ * However, there was an assertion here to make sure that `gfp` was
+ * never set to GFP_NOWAIT/M_NOWAIT. Do we need a specific handling of
+ * M_NOWAIT here?
+ */
VM_OBJECT_WLOCK(obj);
rv = vm_page_grab_valid(&page, obj, pindex, VM_ALLOC_NORMAL |