From: Taotao Chen <chentao...@didiglobal.com> Hi Andi,
> Hi Taotao, > >> Reported-by: kernel test robot <oliver.s...@intel.com> >> Closes: https://lore.kernel.org/oe-lkp/202508081029.343192ec-...@intel.com > > ... > >> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c >> b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c >> index e3d188455f67..2b53aad915f5 100644 >> --- a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c >> +++ b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c >> @@ -514,6 +514,11 @@ static int __create_shmem(struct drm_i915_private *i915, >> if (IS_ERR(filp)) >> return PTR_ERR(filp); >> >> + /* >> + * Prevent -EFBIG by allowing large writes beyond MAX_NON_LFS on shmem >> + * objects by setting O_LARGEFILE. >> + */ >> + filp->f_flags |= O_LARGEFILE; > > I don't have anything against this, but is it really fixing the > issue? I thought that O_LARGEFILE is ignored in 64 bit machines, > while here the failure is happening in 64 bit machines. As mentioned in the commit body, without O_LARGEFILE, file->f_op->write_iter calls generic_write_check_limits(), which enforces the 2GB (MAX_NON_LFS) limit and causes -EFBIG on large writes. On 64-bit systems O_LARGEFILE is still set when opening files (e.g. via open()), so we also need to set it here for shmem objects created inside the kernel. However, on older 32-bit systems, setting O_LARGEFILE unconditionally may be risky. Previously I did not check this, but to reduce the risk a safer approach is to wrap it in a check, for example: + if (force_o_largefile()) + filp->f_flags |= O_LARGEFILE; > > Besides, where do you see in the LKP logs the -EFBIG error > message? > Due to the previous return order in shmem_pwrite(), this -EFBIG was being overwritten by -EIO on short writes. This issue will be fixed in PATCH 2/2. Taotao > Andi > >> obj->filp = filp; >> return 0; >> } >> -- >> 2.34.1
